Post more details if you want a the best answer. How many bays? Does it have a foot bar? Does it come with oar locks? What are the dimensions and what kind and size of raft did it come off of? Does it have decking over the double rails? I'm not quite sure from your description, it comes with 2 seats? Does that mean it's a fishing frame? Not sure. Any other accessories? Is it just Lopros and then regular AL pipe or is it NRS anodized tubing too?
Better yet post pics of your frame.
In general you can expect about 50-80% of retail when selling used on Craigslist or the buzz for something like a frame, depending on the condition, age, and season. A nice all NRS parts frame will probably be on the higher end of that range. Because of the adjustability they seam to hold their value well.
AFAIK posting on the buzz for non commercial items is free.