I'm new to this game as well but maybe further down the road.
First are your motors steppers or servos, bipolar or unipolar ?
You will need a board to suit what ever type you are going to use.
Also depending on the size/power of your motors and machine, wether a simple driver board like the one's available from www.kitsrus.com (K179 or K158) or a more powerful feature packed boards like the Xylotex or NC Step will be the most suitable to your design and pocket.
Depending on your electronic skills will determine building from scratch or buying a ready made board.
You will learn more if you build your own probably for half the price of a readymade unit. But saying that it is nice to just open the packet and wire it up.
The Xylotex board is around $125