looks like a good buy to me. does it start easily? from what i can tell in your pics the tires look good. how do the brakes work? will it sit and idle w/o any help? does the headlight work? shake $300 under his nose and see if he bites. it's not a very fast trike, but it's more of a utility trike than sport. it's a 4-storker, and there is a DG RCM exhaust system on the Dennis Kirk website for it, complete w/ spark arrester. If you put a better pipe on it you'll have to keep an eye on the carb for sure. if it's still stock, you'll definitely need to re-jet. I would recommend a K&N as well. as for safety in the trails...don't be afraid to lean!!! =-) this is my $.02. hope it helps.
86 ATC 250R
83 ATC 200X 12:1 slug, 28mm alky carb, DCM pipe
85 YTM 225DX
81 ATC 250R
83 ATC 70
84 ATC 70 20mm alky carb, cobra pipe
90 LT500R (I know, not a trike but I like it)