As with anything, a lot depends on condition - of the tolex, the grill cloth, and especially the speaker. Good original condition can bring as much as $400, at least it did a couple of years ago. A forum member sold a solid pair of 118Vs not too long ago, which he had advertised a few months. If you look through the "classified" listings on this forum, you should be able to see some asking and selling prices.
You can do your own market research on the site below, to see what people all over the United States are asking nowadays, and whether they're selling.
http://instrument.jaxed.com/cgi-bin/music.cgi?cat=msg&fil=&itm=sunn&state=&ps=&pe=&ys=&ye=&submit=+GO+
To save EdBass from making a post, I will tell you that while condition is important ultimately the buyer makes the most difference. If you are lucky and find the right one, he or she may be willing to pay a lot for a good cabinet. But absent that "right" buyer, you'll have to ask something in line with prices other sellers are seeking.
Good luck!
