The homequiltingsystems group on Yahoo! has a file of used machines for sale. Try joining that group, not just for info about prices, but also for lots of good advice. Longarm quilting for business is very different from longarm quilting for yourself, and there may be some pitfalls you want to be aware of.
Here is a link to the used section of the APQ website. You can compare the price of a refurbished machine with the one you have found for sale. You would expect to pay considerably less for the local one as here won't be a warranty.
http://www.apqs.com/machines_green.php