Tractor Supply has new 4' for $850.
It's been a while but I only paid $750 for a Bush hog SQ600 5' model.
I had a cheap rotary cutter for a while. I bought a Bushhog brand cutter and it was night and day difference between the two. The quality of the cut is much better and if you do need parts they are available about anywhere. You get what you pay for and money is to hard to come buy to waste.