If it was rolled hard , you should make dang sure the frame is okay. A twisted frame can make is steer funny and cause cracks in the gas tank and in engine case. Replacing engine cases cost big bucks to fix. Look it over with a fine tooth comb. Check for cracks in the frame, swingarm and engine. If the engine is leaking oil, I would be sure and pass on the deal. I've never seen an 03 for $1500 but we found an 01 that was mint for that price.
My advice is make a list of everything that is wrong with it and see what it will cost to fix it. It could be cheaper to go buy a new one. On the other hand, you could get lucky.
Best of luck!
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I ride a 400ex, my wife rides a Wolverine, my son mx races a 300ex, my nephew races a KFX450, my sister in-law rides a Eiger, my father in-law rides a 400ex and my mother in-law drive a Rhino. So ATV's are a family thing for us.