I'm sure someone will chime in soon with some good "intro" links, but in the meantime, here's me.
Basically comes down to deciding whether you want a full-power "battle rifle" in a .308-class cartridge, or an "light/assault/homeland-defense rifle" in a less-powerful caliber.
Volumes have been written on the issue. So, I'll just toss out a few ideas, and you can use the "Search" button at the top to conduct further research on whichever rifles seem interesting to you.
Assuming that you want something pragmatic (rather than focusing on collectability or curio value), here's a list of common military-type rifles, and some approximate prices:
Light Rifles:
AK-47 -- $300-700, 7.62x39mm
AK-74 -- "" , 5.45x39mm (basically same as -47, just low-recoil/high-lethality cartridge)
SKS -- $100-200, 7.62x39mm (Soviet rifle prior to the AK series)
AR-15 (civilian M16, M4, etc) -- $700 and up, in .223
SU-16 -- $400, .223 -- rifle by Kel-Tec, simple design, piston-driven, uses lots of polymer in construction.
AR-180B -- $550, .223 -- reintroduction of an "improved" alternative to the M16, similar ergonomics but much simpler (possibly more reliable) operating system.
Battle Rifles
M1 Garand -- $350 and up, in 30-06 but can be rebarreled to .308. Available at that low price through
www.odcmp.com
HK 91 -- $600 and up, now copied in the US by JLD Enterprises (
www.jldenter.com), very cool, very simple, very reliable operating system.
FAL -- $700 and up, formerly most common military rifle in the Free World. Made by lots of different manufacturers though, so research carefully before shopping.
That gives you a rough idea of what fits your sub-1000 budget. Lots of good stuff available for far under $1000. Check out the "Search" function to do some research, narrow down your focus, and if necessary post again with your narrowed-down list and explanation of what your priorities are in a rifle. Good luck in your search, -MV