You'll probably get laughed at (but that never bothered me), but if you want to work your way up (or you may stick with it?), I just added a Bushnell TRS-25 HiRise to a 15-22 plinker that I turned into a poor man's 3-Gun type practice rig.
The more I read about the TRS-25, the more impressive it sounded, and a number of folks are running it on guns with much more recoil than an AR with good results (holds zero, durable).
I even managed to run across a test of cheap $100 red dots, and it passed their (admittedly limited) dunk and drop test (flung rifles with scopes attached) - many cheap red dots failed one or both tests.
I have EOTechs, ACOGs, etc on my big ARs, but so far I've been impressed with the TRS-25. I have a friend that's been piggybacking on my research for putting together a 15-22 on a budget, and also got the TRS-25. His wife has been wailing on muskrats in his pond since doing so, and he has also been impressed.
He's got his mounted on the included OEM riser, which will give you lower 1/3 co-witness. The riser doesn't look bad, but that adjustment screw is just butt ugly, and for some reason the clamp is not full length, which allows it to flop around until you get it tightened.
Cheap, and maybe something to play with until you can check other folks' setup for something later? You could always move the TRS-25 to another gun (assuming you have one).
http://www.amazon.com/Bushnell-Opti...ie=UTF8&qid=1372934145&sr=8-3&keywords=TRS-25
My friend has his mounted as it came - I have a Nikon P22 scope, with the Bushnell mounted on a Weaver Offset Mount behind the scope.
http://www.amazon.com/Weaver-99671-...372934231&sr=1-1&keywords=Weaver+offset+mount
Yeah, the little TRS-25 probably ain't Trijicon / Aimpoint / EOTech tough, but ?