How much depends on your local market and how bad you want to sell it. Check your local Craigslist and then price it accordingly, or under price it if you just want to get rid of it. If you are willing to ship it nationwide, then check prices on some of the big stores (B&H, Adorama, etc) and again price accordingly. Remember, most folks looking at used gear are also looking for a deal, if you price too high, it just wont sell, but then again, there's a sucker born every minute.