Keep in mind we are all prospective clients of yours - getting low balled sucks, but don't expect someone to offer you what you are asking for. That being said, you're haggling with that guy over 75 bucks... That buys us a full tank of gas and maybe a lunch. You gotta ask yourself, "is it worth holding on to and hoping for the additional 75... Or negotiate to 300 and get the deal done?"
Anyway, what would I know - I only sell for a living. Good luck with your sale, free bump.