on eBay [sold items], brand new went for $485-500 per pair. Any cosmetic wear will have to drive the price down from there. by how much, I don't know. Probably $350-400 would be a decent starting point. The lower initial price may attract more bidders and possibly cause bid war or not. It's not a rare item and not highly desirable.
I personally like the sound of LSi and LSI/m series speakers, but generally not on models below these.