How old, dummy?
If it's no more than five or so years old I'd say $125 at most.
Old and worn? $50
Nearly new? $175 tops.
Coleman don't hold much resale price but that dip that was rude and called names is about right.
Don't you just hate people like him
wow tough to find anything without model and year mfg. but to help I think if you call EZ Pawn and other pawn shops that buy stuff and ask...tell them it is heavy and you don't want to be dragging place to place but you'd like an estimate. I would say 350-400 not knowing condition but depending on model up to 1200
Have you looked on Ebay? They seem to have everything for sale so they should have some comparable items.
if your are not worried about making a profit, donate to a local charity, they will probably come pick the stuff up, if you desire the proceeds, take them to a local auction house, just some ideas