Suppose it also depends on which axis cards you'll use. For example, the xylotex board doesn't require/need a BOB -- unless you're gonna put a couple together and need a way to get all the LPT headers sorted out.
I went with the less expensive and am putting 2x 3 axis Xylotex together to get to 6.
:cheers: Jim
BTW the cnc4pc guys were real quick with questions and support
Experience is the BEST Teacher. Is that why it usually arrives in a shower of sparks, flash of light, loud bang, a cloud of smoke, AND -- a BILL to pay? You usually get it -- just after you need it.