I'm going to say this again.
In my books, overpricing a weapon for that much is just trying to be greedy. But then again this is a capitalist economy so who am I to speak against it when it happens everyday.
You can entertain whatever fantasies about prices you want, but unless you follow the guidelines that everyone else follows you aren't going to be able to buy or sell the things you want.
Clean items? Dirty items? What?
It's slang. Clean means tradable and craftable, dirty means either one of both of those things. Dirty items are worth less than clean items because of it.