Browse on E-bay, a lot. Just do a search for SJ_410 and SJ410, you will find deals on there. I picked up a carb three years ago for 5 dollars + shipping, ended up using it last year. I have a $20 4 speed transmission sitting in the garage in case something goes out on mine.
At this point, other then the engine (There was a spare for $50 on craigslist last month), the drive train is mostly Samurai based. Wider axles, actually able to get parts for, but it does require re-mounting your spring pads as the springs are 3" closer together.
Do yourself a favor though, order the clutch from Hawk Suzuki. Some places will list the SJ-410 in their books if they have access to Canadian models, but they usually will give you the wrong clutch kit.
