(POP, cloud of sulfurous smoke) You rang? 
What year is it? They were made from 1972-1976, there were the Mk 1 and 2 and then the JH5. The Mk1 cars had steel bumpers and the 4 speed, the Mk2 had the big rubber bumpers and 4 speed transmission, the JH5 had the big bumpers and the Getrag 5 speed. VIN 18900 was the first JH5. The JH5 had the nicest interior, too. The last 3 or 4 months of production in 1975 had catalytic converters. Those are pretty rare.
On pricing: a rough one anywhere from free to $1k (if it runs), a driveable car in average condition (needs paint, etc) will probably be worth around $2-3K, a nice one in the $7-8k range, a cherry one you'd be afraid to drive somewhere around $12k.
These cars were MUCH faster than anything in their displacement class when they came out. Even the Datsun 240Z, while close, was not as fast. To get anything faster, you had to make the jump to, say, a E type Jag or a V8 Mustang or similar. Compared to today's cars it will accelerate much like a 1.8 Miata. The Miata's suspension is light years ahead, though.
Yeah, Delta Motorsports doesn't publish prices on teh Web. Jim Medland is a helluva nice guy, knowledgeable, easy to work with and interesting to talk to but he does things his own way. 
Check the body for rust in the rockers, that was a problem with pretty much every car of the era, not just J-H's. The 'dogleg' at the bottom rear of the front fenders and the bottom front of the rear fenders is a mud trap, if you see bubbling there rust is likely to be pretty extensive. Just about every panel is available new from either Delta or Martin Robey. Rumor has it M-R is planning a run of 'bodies in white', the way BMH did the MGB and Midget.
The hood prop mechanism on most cars is one of those screwy things the Brits use where you have to raise the hood slightly, push a thumb catch back, then lower the hood. A lot of people have unknowingly tried to just shut the hood and in the process bend the crap out of it. Later cars came with a prop rod which, while a bit more aggravating to work with, will prevent the bent bonnet syndrome.
The engines are NOT fragile, dunno where that came from. The first six months or so of production was beset with oil leaks at the cams and those cams were also too tight in the towers, on a really cold morning (like around zero) they'd stick and jump time. Those cars should have all been fixed by now, if not Loctite 515 is the magic oil leak fix component. By now the cams should have naturally opened up the extra .001 of journal clearance Lotus built into the later motors to fix the cold start thing.
Speaking of cams, the valve clearance is set with shims and is a time consuming thing to do. The engine is like a Honda RFVC in that it should have valve train noise, if it doesn't they need to be adjusted before it cooks a valve. It's best to set the valves .001-.002 loose rather than too tight.
The water pumps have been known to seize, Delta and Dave Bean both have much improved pumps for ~$100.00. Cooling systems will hang right around the midway mark around town, then jump to around 210 or so on the highway. That's not the radiator, thermostat etc it's poor airflow through the radiator. I made an aluminum 'scoop' for mine which solved that.
So far, the highest mileage I know of is 400K on an original bottom end. The car has had one valve job, it belongs to a JHPS member in California. It's his daily driver. They make real nice power, it was rated at 146 HP in US emissions trim. It can be lugged down to ~2k in 4th and will pull smoothly from there but still wind to 7500 RPM.
I know of one engine which had a thrust bearing go bad, much like a Spitfire. I think that one was an aberration, though.
They are interference engines! A lot of people left the timing cover off for whatever reason, if so it should be easy to check the timing belt for cracks etc. If it looks bad, don't drive it until the belt is replaced. If it looks good, replace it at the earliest opportunity anyway. The recommended interval is 24,000 miles. No that's not a misprint.
Look at the carbs carefully, they are the normal for the time Stromberg diaphragm type pieces. What you are looking for is the 'tee' between the carbs for the fuel line. If it's plastic, replace it IMMEDIATELY. They have been known to split and cause a fire since the starter and distributor are both under the carbs. Delta has a brass replacement that works nicely.
The 4 speed transmissions were pretty tough, their one Achillies heel was the mainshaft nut could work its way loose and this led to worn shift forks etc. That can be checked and repaired without removing the transmission from the car. They would start out having a sloppy 3/4 shift and make noise on accel/decel. The Getrag 5 speeds were tough as nails, their only drawbacks were notchy shifting and 5th was not overdrive, it's 1:1. I swapped a Toyota Supra 5 speed into mine, it's not difficult.
Brake stuff is actually readily available and reasonably priced except for the master cylinder, it's been unobtanium for quite some time. The good news is a TR6 M/C is the correct bore and bolts right in, I have one on mine. TR7 calipers are also a direct bolt on (I have a set sitting in my shop, yet another project) and you now have a much larger selection of go fast brake parts. Rear brakes, even though they are drum type, are more than sufficient for anything the average guy might need.
Rear axles don't give trouble. Seals, bearings etc are easily available if needed. The 4 speed cars had a 3:73 ratio, the 5 speeds 3:45.
Electrics are typical Lucas of the era. A brass brush and dielectric grease are your friend. The one complaint I have about the stock electrics is the alternator puts out a whopping 43 amps. Woo dammit hoo. At idle with the headlights, wipers brake lights etc on, the turn signals will start flashing slower and slower... There's a guy on eBay selling a new 110 amp alternator for a decent price, a guy at the last car show I went to said he's bought two for a couple of Minis he has and they have been great.
I mentioned the dizzy placement, it's a PITA to change points because of its location. I stuck a Crane ignition on mine to fix that.
Performance upgrades: there's a car called the Vauxhall Firenza which was never sold here but the Kiwis and Aussies got them. There are a bunch of them Down Under and the suspension stuff is a direct bolt in. Wheels are 4x4 inch bolt circle, stud size is 7/16-20. 100mm bolt circle wheels can be used but will be difficult to center.
The 9xx engine has been pretty well developed over time, there's all kinds of go fast goodies available. The most common J-H 907 upgrade is a 2.2 crank wih JE pistons, then either the 104 or 107 cams and a dual Dellorto intake. Webers can be used but the progression system is lean on a Weber compared to a Dell, making it hard to get a smooth transition from idle to midrange with Webers. An intake from a Esprit can be used to ease a EFI conversion, it's been done before and is well documented (EFI is in my car's futire as well). It's even possible to drop a 910 or 912 (Esprit) motor in a J-H but the crossmember has to be notched to clear the oil pan so the engine will clear the hood.
Hope all this helps. Ask if you have any quiestions!
