Hi Toby,

if you are professional, buy professional quality machines. The faffing and aggro are not worth it especially if you want to remain competitive.

MDF is not a good material to make a machine out of. I have recently made parts for a workshop that realised this after spending way too much money on a machine.
You will probably need to establish how much you want to spend n the machine you buy based on the business you expect to bring in. When you do that, buy the best you want to afford.
Not looked into the woodworking side of things at all but ultimately, you are better off buying something in your home country, especially if you do not have much CNC experience. Importing a machine may lead to issues that are again, not worth the hassle for the monetary saving if any.

If you want to build for the fun of it, then by all means do so. It is very satisfying to make a machine that could potentially make its money back. The cheapest linear actuation would probably be if you used rack and pinion as ballscrews at 8x4 lengths tend to be rather expensive. Keep reading on here and other forums to get more ideas.

R's

George