If it were me, I'd try to find the lowest mileage example of the oldest acceptable model I could. The newer the BMW, the more, erm, challenging the technology. The E9x cars are where I'd look first, as I was never crazy about the E6x 5-series. Whatever it is, an enthusiast-owned car with records will cost more, but it's totally worth it to get a properly maintained car, as you'll be paying to get it up to speed if you don't (figure $1500-2000/year in regular maintenance costs for these cars, and a little more for the E6x, assuming you're paying for labor). If you're confining yourself to local examples you're really limiting the search - fly-and-drive opens up a lot of doors to markets where BMWs are thick on the ground.
EDIT: There's a unicorn manual non-iDrive 2011 E91 328xi in NC on Cargurus right now. Not cheap, but given the rarity it might be worth it.
SECOND EDIT: If you really want to go down the performance rabbit hole, there's this E91 330i-converted wagon: https://www.bmwcca.org/ads/158826
The E60/1 has actually grown on me the more I see them with M5 front ends, but the E91 also looks pretty damn good with the M3 front. I've just been worried about the space w/ the E91 as it seems every UK forum complains about the lack of space in the E91 and holds the E61 as king, just because space and tech.
I've thought about doing the fly and drive option, but I've always liked being able to sleep on a decision before I pull the trigger. Not to mention with my luck, something would be wrong enough with the car for me to pass on it. That 330i converted wagon is pretty damn nice, though.
MPG is not so great on my e91 328ix auto. A manual RWD would be best. The rear seat is not the most comfy especially the middle hump part. Nobody wants to be there for a long drive. 50lb dog rides in the way back fine. Roof rack works great.
The handling is good, it's quiet, stereo is OK. I like the a pano roof and it's fine on the e91, the e46 was a problem for it. Braking is strong, AWD is seamless. Power is adequate, another 50hp would be welcomed.
Failures so far in 2 years: rear wiper pivot seized $125, battery $240, passenger door handle shorted so no more comfort access on it $150 for diagnosis, driver door handle is intermittent on comfort access now. Replacements are $600 each. Eccentric shaft sensor died from oil infiltration $1100 covered on extended warranty.
I like the idrive. Voice recognition is sketchy, but nav works well after I updated to 2016 maps. Heated steering wheel is the BEST feature on the whole car.
The unicorn to get would be a manual RWD with sport seats and sport package and heated steering wheel, of course.
Thanks for the insight! A manual RWD touring truly would be ideal, but the rarity of them is a pain. I'm not even sure if a manual swap at some point would be possible/worth it with long-term goals. My daughter is still in a car seat thankfully, so I don't see the back seat being a big concern. It's nice to hear that a decent sized dog would be fine in the cargo area, though.
There's currently a '06 530xIT for $6k w/ 150k miles by me. Every package, including Sport. Then an overpriced (compared to a few ads I've seen 200+ miles away) '08 328xIT w/ 92k for $12k by me. No packages if I remember correctly, though.