I'm going to assume that your budget may be a bit tight for Strider quality (as you were asking about the $49 modstream deal) and mention the
OCZ Z-Series 650w for $65 (AR) from DirectCanada. The OCZ-Z series seem pretty basic (made by PC Power & Cooling at least) but are supposed to be 80+ Silver (up to 88% efficient) but not much info/reviews are available yet.
I just picked up this unit (Z-Series 650w) and I'll be testing it out tonight.
2c