No, not really.
Sure, there are "range toy" grade RDS that will give you years of service at the range for under $100. My favorite example of these are the products sold by Primary Arms
http://www.primaryarms.com/category.sc?categoryId=419.
I have 3 of these for .22 rimfires, and my kids airsoft guns. Work great!
However, these are not "weapons grade" (bet your life on them reliable, bat them across a gravel parking lot without loosing zero tough, submersible to 80 ft in sea water with 5 year battery life) and are not sold or advertised as such.
You bought a DD AR instead of a nice Hess / Vulcan right? Don't skimp on the optics. Save up and get an Aimpoint, EOTech, Trijicon etc (buy a gently used one or one of the non milspec versions and save your money there) and you won't regret it.
You get what you pay for, buy once cry once, YMMV.