For similar type of rifles, you'll get aside from the AR15/M16 clones: Bushmaster ACR, Ruger Mini14, Robarms XCR, IMI Tavor, FN FS2000, Kel Tec SU16, Swiss Arms CQB/Carbine/Classic, H&K MR223, H&K SL8, Benelli MR1.... To name a few.
Some of those guns will require more work than others to get a more "tactical" type of gun.
Depending on the gun and barrel length, some of those are restricted, and some non restricted. For example and Bushmaster ACR is restricted with its factory 16.5" barrel, and non restricted with an aftermarket 18.5+" barrel. As with most of those guns, if you want a shorter barrel (must be a factory made barrel in that length, not a cut down) you can get one and re-classify that gun as restricted, although most of the time it's a pointless endeavor. Prices for those guns are all over the list, from 800 for a Norinco CQ556 (a Chinese AR15) or the SU16, all the way up to over 4 grand for the HK MR223.