First is the KE Arms Enhanced LPK - $24.99 http://www.primaryarms.com/ke-arms-...r-parts-kit-ambidextrous-selector-1-50-01-346 I have looked around and not found a lot of reviews on this, but it is in stock a lot of other places for anywhere from $60-90 I think. Then there's Black Rain Ordnance kits for $26.99 http://www.primaryarms.com/black-rain-ordnance-223-lower-parts-kit-pk-lr I was going to buy 6 or 8 of these and then I read the reviews. I would have expected Black Rain stuff to be at least adequate... but I don't know if they've started buying their LPKs from a cheap importer recently or what, but 4 out of 5 reviews on Primary Arms in the last 4 months or so were horrendous. I dunno, take your chances if you like, just throwing it out there. I think I may order some of the KE Arms kits just to give them a shot.