What can you tell me about the Burris AR-536 5X 36MM Prism Sight? I'm planning to buy an optic of some form for my AR, I realistically see myself shooting at 100 yards.

I'm going to bump this, because I'm considering this sight myself. I looked at one yesterday at Outpost Armory (Ronnie Barrett's place) and they had a great deal on it. It seems to be light enough (I have a GII Lite Hunter with nothing added except Troy back up sights and a steel gas block to mount the front sight) to fit in with my light rifle plan, and seems to have good clarity, as well as reasonable adjustability. I do not need a mega buck sight for this rifle, it is not s long range sniper rifle, just a good solid rifle that can serve as a medium range semi auto target rifle, a medium range hunting rifle, and an MBR. Are there any known problems or real shortcomings concerning the Burris AR-536? Is there something better in the under $500 price range that offers light weight, a 1 MOA or smaller dot, and decent function as a close range red dot sight and a medium range optic?

Check out the primary arms versions

I have one. It's quit good for what it's. Good resolution and decent contrast, daylight visible illumination.

Not as bright as my ELCAN nor has the field of view but it's 1/3 the price.

Another vote for Primary Arms.  I like the reticles better- especially the 2.5x.

Agreed with others have said about the PA reticle being better than Burris, however, at 300 yds or less, a dot is a dot (when zero at 200 or 250 yds) and you don't need all the other BDC markings so if you like the Burris, get it.  I have the 1x and 3x versions and they all serve the purpose just fine.

The 2.5x is an extremely under-appreciated optic that belongs on many budget ARs.