I just bought and Aero Stripped lower.
I live in CA so I've opted to build it with the AR Mag Lock instead of losing
some of the other features.

I was just going to keep it simple and use all Aero parts but everything is out of stock with
no apparent end in sight.

I'm looking for suggestions on what to use for a Lower Parts Kit.
my local gun shop is recommending Spikes Tactical.
Some other brands that have popped up with online research are:
CMMG & Rock River.
They all seem to be comparable in price.

Advice?

I'm not aware of Cali laws so I'm going to assume you can use any parts kit to build your lower.

Most mil spec parts kits should be good to go.
If you're using this as a range toy, I personally wouldn't try buying top tier parts kits. CMMG is popular. Psa makes kits and have sales a lot. There is a lot of other smaller names that make decent kits too.

Take your pick.
I would use any of the kits on that page for a build without question. Even the Anderson kits I've used have been fine.

But this is what I would get, since mil-spec triggers suck so bad.

Rock River

Scroll down at that link and get the Rock River LPK with two stage trigger for $129.
Best trigger for the money in my opinion.

What he said. Factory triggers suck and the RR National Match 2 stage is very good bang for buck trigger.

LPKs tend to be mass produced hardware: avoid very cheap but pretty much everything else is GTG. PSA stuff is as good as any in that regard. If you plan on using your rifle outdoors in very cold weather, make sure the trigger guard is big enough to allow you to wear gloves.

One word of advice: your Aero Precision lower is threaded for a 4-40 setscrew to secure the rear takedown pin detent. If you ever wind up removing the end plate, the spring is secured in place by the set screw. The only issue is that it doesn't include a 4-40 screw and the Allen key for that size is not on a standard set of Allen keys. I had to buy a Wiha micro set to get the (IIRC 0.015") right size. Other than that, love everything about the Aeros.

Use a white grease to cover everything that isnt readily accessible: detents, springs, etc.