i would mention thats its unlocked. in the description, jus say that its unlocked but can be relocked if the buyer wants it relocked. you could also offer to ship it with whatever rom the buyer wants. ive sold thousands of electronic items on ebay. the more you can tell the bidders about the item, the better
i would list it on ppcg first though, that way there is a chance you dont have to pay those ebay fees