$70 or less - only if you buy in quantity 3-5-or more. Best online advertised price are AERO lowers from surplusammo.com. AERO makes uppers and lowers for Armalite and many others. Buy 10 for $64.99ea, not incl shipping/FFL xfer. For you, being in Oregon, you might be able to scoot up to surplusammo in WA state and pick'em up cheap then.
Locally at the gun shows here in Houston, and Florida (where I picked up a few), lowest price was $85 for a Delton, $100 for RRA, more for everything else.