Where can I buy at a fair price?
Some Ive looked at online are $200.00 or more. $100-$150 seems more like it.
No Jig needed.

Nothing 80% is cheap.

stealth arms

I think almost everybody is reselling stealth arms.

If it must be Aluminum, make sure it certified 7075 Alloy and also make sure
it is cut (frame) for a ramped barrel (typically a Clark/Para or a Wilson/Nowlin
style).

Stealth Arms has a very good rep for making a quality 80% AL 1911 frames...

You will likely need a drill  jig, unless of course you have a accurate Mill with
preferably a 3 axis DRO or a accurate way to drill your holes and cut your
slide rails, etc.

Good luck.

A lot of people have used the stealth frames (gi barrel seat) with no problems. The way I see it if the feedramp gets peened you can cut it for a ramped barrel later.