Kickstarting my RepRap project again, I splashed out on four NEMA 17 stepper motors from Zapp Automation - four SY42STH47-1684B motors. Good service, arrived quickly and well packed.
I needed a stepper for an extruder, so I got 4 to give an easy upgrade path to a mendel.
I'm currently running on generation 2 electronics, so I also need another stepper driver. The gen3 boards are great, but they are out of stock at the moment, and because they're fully populated, they would replace my current setup - not a problem, but an expensive upgrade.
While looking around, I found a couple of other posts on this subject:
Casainho also grabbed one of these motors and is looking at driving it with a Pololu Stepper driver board.
Bothacker posted about his electronics setup which uses Sparkfun driver boardscontrolled by a Seeduino Mega.
I really like BotHacker's approach. It's modular, so it's easier to upgrade and slightly more flexible for re-use on other projects, and the seeduino/arduino split for extruder heads can be skipped to start with (as most only have one working extruder) and added later if required. It woul probably be more expensive overall, but is probably more readily available - the driver boards are replacable by other manufacturers, other mega/seeduino controllers can be plugged in. The connector boards are easier to design and manufacture at home, reducing the bottleneck of available boards.
I'm currently leaning towards BotHacker's approach.