Bought my M&P used for 4 and a quarter. A lil bit more than what you're looking for but not much really.
I'm not sure how you feel about used guns but I've been finding alot of BARELY used ones coming into the local gunshop here.
My M&P looked as if it was never even taken out of the original box.
Used Glocks and XD's can be had for pretty much the same price also.
"When the mind fails to comprehend, the body must be punished" -3rd Battalion,Parris Island
Have you handled the M&P? I like the way it feels, but everyone is different. I had a Para .45 in my hand the other day and it felt sweet, you know when your holding the right one for yourself. Go handle them all. Your going to get recomendations for all different types, but in the end its whatever your happy with.