Steppers good and drivers are ok but you will find equivalent much cheaper on eBay internationally and 75 volt would be nice.

The breakout board you have chosen is opto-isolated which would be good except the drivers you have chosen are already opto-isolated ... that makes it slightly more difficult to wire up and can lead to issues so it's best and also cheapest to use a breakout board which is not isolated or even just connect them directly.

The 48V supply is ok, but again 70V would get higher torque. It's also very expensive ... so go for this one if it's still availably and you stick with the 50V drivers:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...ht_1179wt_1139

Though it looks like Zapp might have bought the lot to sell them for three times the price:

http://www.zappautomation.co.uk/ep00...b64aaf46d5274f

I dislike the way they are making so much on those bye claiming it's a good price by saying the RRP is £280.