From another thread, someone suggested just buying an IRO 26" rear wheel with a fixed/free flip flop hub. You don't have to screw around with the spacers etc and for $90 it sounds like you'd save a bunch of time and effort and have a brand new wheel all built up.
Unless you really want to experience of building up the wheel and playing with the spacers which I can totally understand. Money/time wise though it seems like a toss up, depending on how you value your time.