You said this was a triple - is it a compact triple (50-39-30)? Or is it a traditional triple - 52-42-30?
1000 miles on the crank set will have scratches and scuffs. A shop will not be able to sell the crank set as new. If you can get credit, I would request $150. If they aren't willing to go for credit then I would suggest you try selling it for the same amount.