internetrush,
First,...Welcome to the group!
Second, any of the AR-15 varients would be more like the M-16A1 you are going to be familiar with(soon). They can be had for somewhere between $750-$1000 depending on what you want it to look like.
The Ruger Mini-14 would be more closely assimilated to the M-14A1 (civilan M1A1), the namesake for the Ruger rifle, as they both operate with a gas operated rotating bolt.

Rock River Arms and Bushmaster would be my 2 suggestions for an AR-15.