So it looks like inexpensive lowers no longer exist unless you go polymer. Surplus Ammo just got a new stock of saa lowers and they are now $99.99. Just last month the old ones were going for $60.
surplus lower

That's also a completely new lower they are producing. Notice is says SA15 not LOW15

Midwest had the older versions in for $70, but are sold out now.

Link to Midwest with pic to compare also

SAA (the lowers, and the online site www.surplusammo.com) and Surplus Ammo & Arms, LLC are not the same company.
SAA (www.surplusammo.com) is the online site with their own FFL, state, and city business licenses.  Different tax ID for the state, etc.  They are the manufacturer of the SAA SA15 receiver.
Surplus Ammo & Arms, is the physical store currently in Lakewood.  They are the manufacturer of the LOW15 and LOW16 (aka "Reaper") receiver.
Different companies with the same corporate head essentially.  Think Volkswagen and Lamborghini.  Both are part of the Volkswagen Automotive Group.

I know, I know... it says the brand is Surplus Ammo & Arms.  It's not.
Think of it like a franchise if that makes it easier.  Ford dealerships and McDonalds are free to set whatever prices they want for their Mustangs and Whopper's.  Similar to that.

Prices have gone up.  A lot.  People are panic buying again and supply can't keep up with the insane demand.  People went through months worth of ammo production in two weeks.  Gun makers were already back ordered and this just made it worse.  Just about all guns are going up because of the huge demand.  There are a lot of first time gun buyers worried about the President's statement that wants to look into reinstituting the assault weapons ban.  Then Feinstein's desire to also eliminate transfers of banned guns.... so even if you have a "pre-ban" you can't get sell it, and if you want one you still wouldn't be able to get it.  It kicked people into a buying frenzy.