Just did a quick search on Mr.pinball - one for 1400 and one for 1900. they are probably not way off base at 1650 - but I bet most go for 1300 - 1400.
I have nothing to base this on but I think this one is going to rise in value soon- its actually a good game and has a fun layout - and seems to be drawing more interest.
http://www.xmission.com/~daina/classified/search_for_sale.cgi