E46s are cheap now because not only they are aging, but because their maintenance is costly. However, it sure as **** best looking and handling car I know of for road cars. I would take e46 over e90s unless its 1M, M3, M5 or M6. I would have to think about 135i and 335i long and hard.
Anyways, e46 parts and documents are everywhere. However, if you are stuck with a malfunction or get in to a small crash, expect spending a lot of money at the dealer, or getting total loss claim from insurance company.
PS. Rear subframe cracks, thats all I gotta say, everything else can be fixed aside that and frame damage.