Having just gone through this process I can say that while converting a car is easy, there is some thought and lots of little questions that you'll have to ask and have answered if you've never done it. I went against the grain and went with a dual battery configuration and have only gotten it running tonight but I'm completely happy with it. Can go from Mild, wild, and insane by changing the battery setup.
I've always been a fan of the Jammin (hong-nor) cars. The X2 should have parts for a while. I can still easily find parts for my X1cr and X1 CRT.
www.nitrohouse.com has them galore (offshoot of OFNA the importer of Hong-Nor and Hobao RCs). The cars are tough as nails, and at the time of production top notch in handling too. Against today's stuff they'll be just as tough, but will probably lack the agility of modern designs. Designs seem to have moved towards a nose heavy design to increase steering response. Older 1/8th scales are rear biased.
I picked up my X1CR FTE buggy about 6 years ago for $150 used on ebay.
5 years ago I picked up my X1 CRT Pro on ebay for $450 minus engine and receiver. It came with new digital servos and all the other goodies. At the time though it was a new truck and still the flavor of the month so I paid nearly full price for it.
I like to keep all of my cars "in the family" so that parts sharing is a possibility. That more than anything has kept me going on rough days.