Not sure what you are going to be using it for, wood or metal but if you are going the wood route then I would build your own. Its cheaper in the long run and you end up knowing your machine inside and out. Wood also allows more forgiveness on tolerances but metal needs to be precise to something like .002 at least. When I pool some cash I am highly considering one of these:

[link]http://buildyourcnc.com/blackToe2x4v40.aspx[/link]

They are relatively inexpensive for the precision they offer and it will cut up to 2' x 4'. More than enough room.