It depends how quick of a sale you want. Remember skates aren't like a shirt or something, they're sized pretty specifically, you gotta find someone who wants figure skates and is that size.
Anyway, my last pair of boots was used, used for 3 months. Looked pretty good, though used. They were Edea Concertos. $700+ boots, and the seller told me he got them extra stiff from the factory (which you have to special order.) I paid $160 for them. He was selling later a pair of new or worn once or twice or something like that, non extra stiff boots for $160. In my case, the dynamic is a bit different being a guy, as there's not many sellers, nor many buyers of black boots in a relatively big size. So $160 for a $700+ boot.
I also paid $80 on here for a pair of MK Professional blades ($200.)
Of course if you're willing to wait longer for an item to sell, you can make more money, but sometimes the difference can be like months.
I'd say in your case, upper limit of $175, lower limit of $100. If you want to make it better, if you post an ad in your rink's bulletin board saying "$175 negotiable" and see what you have to drop down to, as you may get lucky and not have to drop at all, or have to only drop to, say, 150. But if you want a quicker easier sale right now, I'd say about $100 would be reasonable.