What is the least expensive system that functions like an AR with the controls in the same place, last shot bolt hold open etc?

I want a trainer that functions and feels just like a full size AR.  What is the best thing going right now?

I'm very happy with my M&P 15-22.

CMMG has all the features available of a standard AR. Bolt hold open, forward assist, cotter pin holding firing pin. roll pin holding extractor.
Real AR upper and lower. The mil spec lower can be used with 5.56 upper or variants.
Uppers start at $349.95 complete. Forward assist and BHOA are optional.
Dave

Aim Surplus has the CMMG upper (M4LE) with 1 26 rd mag for $369 currently. Link This includes free shipping.

The ATI/Chiappa upper can be had for ~$300, if youb shop a bit, but is not anywhere near the same class as the CMMG offering above and won't offer the BHO feature you mentioned being necessary. For the difference in price, the choice would be obvious, IMO.

I know of no other dedicated .22 upper in the price range, and of the more expensive offerings available, there is no equal to the CMMG platform. Again, this is just my opinion. YMMV.

ETA: As of now there are 3 left after I placed my order for one this morning.

303.xx at Cals Sporting Armory but no mag and no BHO...

http://www.calssportingarmory.com/CMMG_U_M422_16SI_Sierra_22_LR_AR_15_Upper_p/cmmg10298.htm

Be aware, I've seen a couple guys complain that these are being sent out with the old bolts, not the new Evolution bolt with live round extraction, cotter pin ect..

All bolts being sent out by CMMG do have live round extraction. There are some that do not have the cotter pin.
So the ones Cals is sending could possibly be new bolts without the cotter pin.

+1

I have several .22's.  The primary is a Tac Sol M4 and it is a great gun, but lacks the bolt hold open.  I have a Ceiner conversion that runs great and I switch it between .223 guns, but it also lacks the bolt hold open.  I find the CMMG bolt hold open unit cumbersome to switch between rifles, so I haven't been using it for the Ceiner.  I also have an M-261 for my retros when I want to use a conversion, but it also lacks the bolt hold open.  Fortunately, all three of these run great on cheap ammo.

However, if I were in the market for a realistic .22 I would go for one of the CMMG offerings listed above.  In my limited dealings I find their products top notch and the customer service is always outstanding.  You can't really beat the price or the innovation and they replicate the .223/5.56 the best.

Beware of Cals as I am one of the guys that bought one of the CMMG uppers thinking it was a 2nd gen and when it arrived (Tuesday) it was a first gen.

What type of magazines do the CMMG take?  I have a ton of Black Dog mags.  Will these activate the BHO?

The CMMG will run BDM mags. The BDM's will not activate the BHOA without modification. This is installing a BHOA follower and spring. It also involves gring or filing a 45 degree angle at the rear of the feed tower. Some of the BDM mags need to have the feed channel smoothed. Some need the feed tower filed down. Information on this is in the CMMG forum. Search the threads on mag mods.
I tried the BDM mod and it wasn't worth it. Buy the CMMG BHOA mags for activating the BHOA.
Run the BDM mags when you don't want to use a BHOA.
Dave

What was the final outcome? Did you send it back to Cals. Other than the bolt hold open and the cotter pin/firing pin what is the main difference with the gen 1 guns?

I got 2 emails with one telling me to contact CMMG because it was their mistake and another one with an authorization return number allowing me to return it, so I shipped it back to them yesterday requesting a refund.