It's a nice machine if in good condition. I had one as a stopgap about 18 months ago while I was waiting for a replacement 17" MBP to arrive from Apple and I was pleasantly surprised at how useable and useful it still was. $250 seems a fair price.
$250 is a good price for one. Especially if its the dual layer superdrive model with the high resolution screen. For a 15" or 17" even $300 isn't a bad price if its in good shape and the battery still works.