I'd say somewhere in the range of $2.5k - $4k. That being said, while it may be worth that... it's really only worth what someone will pay and accounts at that range are notorious for taking years to find a buyer, if ever (unless the seller is well known).
Have you tried selling this to chicksgold.com? I sold a worse account to them for $400, so you should be able to get around what you're asking for from them.
I can't buy this acc atm but I would recommend just taking your current offer of $2,500 BTC. It's not that far off your asking price and these higher end accounts can take ages to find a real buyer