Blake,
I would've thought that parts and components for 1/18th scale cars are harder to come by than 1/24th scale models. I guess I was mistaken. Cool projects.
There is WAY more stuff out there for 1/24... 1/18 is just starting to come around with wheel sets and motors.
Broken/damaged cars or cars with bad paint can usually be had for decent deals, so it's a little easier to stomach parting them out
Other cars are still the best source for parts. Most guys that mod end up with 1/18 junkyards full of cars that have been scavenged lol.
I bought an entire car just to steal the air cleaner decal for my 442 lol