The best I've found is about $60 ::gasp:: a pair!?!?
$60/pair may sound like a lot for windscreens. The DPAs I think are around $40/pair. (Check out the prices on Schoeps windscreens sometime for sticker shock!!)
But the way I look at it is:
I've already spent a boatload of cash on my gear and I'm not going to let a cheap, crappy pair of windscreens hose my recordings.
IMO, it's a small investment to make to ensure your outdoor tapes come through with quality.
Sorry, I don't know of a retailer that sells them for < $60/pair.