I paid $280 for mine new a few years ago, so I would try to work him down some. A factory buttstock is fine. If you're going for more "defensive" use, a youth-sized stock may be your best bet (this is what I use on my 590A1). You can find them on ebay fairly cheap.
"Throughout history, it has been the inaction of those who could have acted; the indifference of those who should have known better; the silence of the voice of justice when it mattered most; that has made it possible for evil to triumph."
-Haile Selassie I