CAGs typically recommend Cowboom, but personally I'd check out local pawn shops. If you find one that has a good return policy and has a bunch of stock of the stand-alone console, you could try to haggle down their prices (which are around $40-$60 used, depending on the shop), and try it out right away without having to wait for a mail-in. Safer proposition than eBay as well.
Occasionally I will see new Wii console bundles on sale / clearance for around $100, but I haven't seen them consistently cheaper than that at retail.