I'd recommend getting one that has a jig. In NC i was a member of a group of 5 guys who ordered them when the company was starting up, $35 each lower. Find a guy with a drill press. I had to move before they shipped out though, so someone else got my lower.
Legally, each person has to do their own lower. Someone else cannot do the lower for you, just forewarning.
http://www.sierranevadaarms.com/index.php?main_page=index&cPath=42Here's what we ordered.
Lower is 75, jig is $25. Multiple people can take turns with the jig. Sierra Nevada also offers anodized from them too. You'll just have an unfinished inside.