I think that is way too much personally. Depending on the item you can get up to 1/2 retail IMO
Carboys...$25
kettle? Is is SS, come with a ball valve?
Auto Siphon $15 new
Bottle Tree $35 new
Plastic stuff is hard to sell unless it was never used. I would never but a used brewing bucket, airlocks..etc.
Your best bet is to list out everything with pics and prices, at the very least prices but be prepared to provide pics on request.
just my .02