Seems like a good deal to me. You should be able to rebuild the top end yourself for under $200 total including piston, valves, and machining. That's what my 1965 top end ran me. Easy job to do.

For comparison, I just paid $2300 for a 1974 ct90. It's in excellent condition with only 390 miles. It needs nothing but a good wax job. The price was steep, but I had to have it!