I'd suggest an auction to find the best price. EBay can be a good bet, but you'll pay a fee. The other options would be some of the Facebook groups - perhaps Echo Base Auctions or Star Wars Palitoy Collectors, where you'll find most of the potential buyers and have no fee to pay.
The other option on Facebook is Deal or No Deal where you put the item up and ask for offers. Its a bit like an auction but you can choose to take an offer at any time, or not sell if you don't want to. Theres a dedicated Deal or No Deal group on Facebook, or Jabba's Court Facebook group also allows this format.
Good luck with the sale and please post here if you do offer it up - I'd be keen to have a bid!