For a car with that low k's, expect premium price (if the body is mickey mouse). But, as mentioned, I wouldn't pay any more than ~$18 if it's untouched. I'm driving an '06 bought from Graeme Powell Mazda and has had next to no issues. I don't track but like to give it a squirt every now and then.
If it's stock height, chains will be tight but should fit.
As for problems with them, there isn't anything will go without some serious thrashing. If you mod it, remember that money is needed. Just check the engine mounts. They wear quick with the torque these things put out. Suspension also gets a little rattly rather quickly. Everything else is standard wear and tear items.
If you're looking for a $20k car, maybe look into the Gen 2 since they come with SatNav and the Gen 1 doesn't.
3 MPS - Rolling on Pirelli PZero Neros, sitting on Bilstein B12's, stock internals... still makes me smile with the Zoom Zoom.