Cheap Alternative to Pelican Cases?

I've got a wacky idea to turn my TL1000-S streetfighter into a hooligan-commuter-tourer by slapping a big ol' case where the passenger seat should be. Ideally, I'd have something along the lines of a Pelican case - waterproof, sturdy - but cheaper. I'd be surprised if the military didn't have something along these lines for equipment or ammo, but I don't really know what I'm looking for.

Something the neighborhood of 20" cubed is about right.

If you have a suggestion for a cheaper alternative to a pelican type case, especially something that might be found at my local surplus stores, I'd appreciate it.

Ooh, like these:

http://www.cases4less.com/detail_skb_milstdp.html

Our local electronics surplus store sells a ton of cases like that. They are next to the Prius motors, past the missile housings. They have an online store, too.

SkyCraft Surplus

I've been looking for a case like those for carrying around my paintball stuff. Nice finds, I just hope I can afford them!

try hardware stores, I was looking for a dimond plate hard case for my camera set up a few years ago. Photo suplie catalogs and stores ran 80-100, lowes had one for 25. Not quite what you where looking for, but it is worth a shot