To get ballscrews, look to China if you are price conscious, guy called BST Automation on Aliexpress site, will have all you need, is very helpful and prices, well, I just bought all the motion - linear rails, carriages, ballscrews, nuts, brackets etc for my mini CNC build for the price of a couple of screws alone from a UK supplier.

I usually shop UK but I could not have done this build if I had.