I know this type of thing has been discussed many times, but I'm lazy and discussions are fun....

My only AR is an M&P 15 Sport II.  This is my general purpose HD/SHTF/Range rifle. Until today, I had a borrowed Aimpoint Comp M2 on it, along with the stock folding MAGPUL backup sight. (Standard front post)  The M2 has to go back to the owner (long story - not going to tell it here).  I don't care for the mbus sights - especially as a primary sight - so I find myself in the market for a different optic or sight.

I like the carry handle rear sights on Colt rifles, but I loved the M2.  I had originally intended to get a Bushnell TRS-25 before the m2 landed in my lap, but now I'm worried that I'm not going to like the TRS-25 after using the m2.  

I can get the trs-25 for $60 +/-.  Would I be better off with a carry handle?  Can I get a decent carry handle for that, or is it stupid to replace a red dot with irons, when I already have useable backup sights?

What says the hive?

Get another Aimpoint. Your choice which
And carry handle mounts all suck.

What am I looking at for a functional (doesn't need to be pretty) m2 or m3?  Prices seem all over the place, and i know theres an issue with counterfeits. Where is a safe place to pick up a used one?  (I'm poor - pretty safe to assume even an m3 is likely north of my budget.)

I have an aimpoint pro and a bushnell trs-25 . I use the trs 25 on my pistol caliber carbine uspsa matches and have no issues . the dot is round like its suppose to be , I have yet to have it wash out in bright sunlight the difference is the aimpoint pro has a 2 moa dot and the bushnell has a 3 moa dot . since you said the rifle will be used for home defense then between the two the only real choice is the aimpoint pro . turn it on and leave it on battery life is not an issue my last battery I changed at 3.5 years and it wasnt dead yet I was just paranoid . the down side to the trs is you have to turn it off or the battery will run down , they do have decent life but none the less it wont last like the pro . I have also found the dial to be a bit stiff . not much of an issue for competition but at 2 am trying to grab your rifle and turn it on while seeming simple it is not . personal experience with coyotes in the barn yard and a german shepard going nuts at the same time . just my 2 cents but for serious stuff save your money and get the real deal , for punching paper , hunting or fun then the trs is a bargin .

Yeah, get a compM3 used. Great optic