Definitely have a look on the completed items on ebay to see what things have successfully sold, and what they sold for, as this will help you to determine the rough market price for your items (particularly the LE stuff).
Whatever stuff you have to list, is worth trying to get rid of - not everyone will buy used lipglasses etc, but as long as you clearly have them listed as used and are truthful about it, then I would agree that it is the buyers decision whether to buy it with that knowledge.
Also, think about how quick you want to get rid of it- if you need it gone now, then the price should reflect this. On the other hand, if you're happy to wait until the person that really wants that item comes along, then price it accordingly. For example, I want queen's sin lipstick - since I've started looking I've seen ONE come up on ebay - priced at $78 with $10 P&P- to me, that's a price for someone whose desparate for the lipstick, and I would imagine it will hang about a bit.