I bought 8 lower parts kits under 40$ just to see what I could see. What did I see? Big differences in what I got. Two of the right under forty ones were full of what looked like MIM parts. They worked and felt okay when fired but the main components being the hammer and trigger were narrow on the width on the arms allowing side to side play along with the what to me seemed weak retention of the hammer pin allowing more side to side movement of that pin. I don't hate MIM but please remember shrinkage in manufacturing on what I think are critical dimensions.
I checked to my satisfaction an on sale for 24.95 CMMG lower parts kit. I was surprised it came packaged in a nice plastic hanger display ready clam shell with the parts grouped in individual plastic bags. What I got for the on-sale price was astonishing. Parts checked to my specs specs I have with no regard to their own good ones for pivot and takedown design. The trigger was cut out at the back like an m16 style trigger so I might remove it and put a replaced value rating on the kit. Other than a shiny mag catch button I got, the rear m16 style cut on the trigger, and the side to side play at the hammer pin with the pin I give it a hell of a buy at under 30$. Sorry folks the sales buy has gone. but remember it could be sold at that price. Nice kit for the normal even the sales price.
I will add more for the other ones but it is late and I guess not many are buying kits on the cheap like I did.
I got one of the BCM sold as commercial kit for around 35 dollars. Great kit for the money. Trigger felt as good as any mil spec I tried and the parts checked out or looked really nice for the price. I hate when they are gone at that price.
Some of the other lower priced kits have parts I would question and or replace parts if I was to try and use them.  Funny thing is some I could be replace the parts and still come out with a cheaper lower kit below 30$ while one I received I could not.

I have also found the CMMG to be very good for the low price point.

I've used maybe 8 CMMG kits, zero issues. I generally recommend them to any that ask for recommendations.

That sale was crazy good, if only it wasn't OP.....

The last CMMG LPK I bought also had a trigger with the tail cut out like an M16. I thought that kind of odd.

Which kits had the MIM parts?  I haven't gotten any in a kit so far, but buying individual parts I've received a hammer, trigger, selectors, and a mag catch that were MIM.

BCMis still showing the commercial LPKs at the $35 price.

Anderson kits contain MIM components.


EDIT:

A more accurate statement would be that many Anderson kits contain MIM components.

The Anderson LPK I bought had MiM parts.

cmmg is top shelf.  bought a bunch recently after examining the first one.  incredibly smooth for a milspec trigger, other parts are well made.

CTD had them on clearance for 25 ea but that seems to be over

prev. to that i was buying anderson and they are SHITE quality.

+1 for CMMG. Their take down and pivot pin diameters are on the large side too, which is nice.

CMC and Aero kits are nice too and not too pricey IIRC. Both come with parts made form investment castings, matte mag buttons and the aero kits have "S" marked safety selectors.  Parts are all phosphate too and not nitride.  Nothing wrong with nitride - I just like the classic look.  Saw a nitride castle nut recently that made me cringe a little

I feel the same way.

What did they measure at?

I just measured 3 Colt Schmid marked Triggers, all measured exactly the same. Measured 3 Colt Hammers, 2 were Schmid, measured exactly the same, the 13629 cage code hammer measured .004 narrower.

All 6 parts originally came out of new Colt rifles.

The narrowest was a mim at .668". One cast one was .670".  I have one mim one that is .665" but it was from a kit a couple years back

So far to replace the needed kit parts I received and make the fcg perform as it should be in my mind and with any other out of dimension parts in the kit without shipping cost has made it a 40-dollar average for all the kits,

I've had good luck with CMMG, Aero, PSA & Stag.

I only use a mil-spec trigger in the AR9. Most everything else gets the Larue MBT-2S