If you are really wanting to stay at or around $600, you can't go wrong with a CMP "service grade" M1 Garand. I hear that their current batch of Springfields and H&R Garands in "service grade" condition are really nice. Furthermore, at $600, you really won't ever have to worry about throwing your money away on something that'll depreciate in value. I have a Winchester M1 Garand that came from the CMP several years ago as a "service grade" rifle, and it shoots wonderfully and is in nice condition. A nice M1 carbine may be another option from the CMP.
Another rifle to consider would be the French MAS 49 series of semi-automatic rifles. The MAS 49/56 carbine is commonly found for under $400, and with careful searching, you might even be able to locate the uncommon MAS 49 rifle for under $600.
Other than these, you might be able to locate a Hakim. At $600, you'll likely be dealing with a lot of Century builds, which I haven't heard great things about. An Arsenal AK-47 would run about $700, and I've heard lots of great things about those. Personally, if I had $600, I'd save a bit more and find a good Arsenal AK, an FAL, or an SVT-40. The prices on the SVT-40 rifles are dropping a bit right now, and they are really interesting rifles with a lot of history. FALs can be a bit expensive, but I've seen several nice rifles sell for less than $1000 with Imbel receivers.
Needless to say, you have a lot of good options. It's just a matter of what YOU are interested in.
Another rifle to consider would be the French MAS 49 series of semi-automatic rifles. The MAS 49/56 carbine is commonly found for under $400, and with careful searching, you might even be able to locate the uncommon MAS 49 rifle for under $600.
Other than these, you might be able to locate a Hakim. At $600, you'll likely be dealing with a lot of Century builds, which I haven't heard great things about. An Arsenal AK-47 would run about $700, and I've heard lots of great things about those. Personally, if I had $600, I'd save a bit more and find a good Arsenal AK, an FAL, or an SVT-40. The prices on the SVT-40 rifles are dropping a bit right now, and they are really interesting rifles with a lot of history. FALs can be a bit expensive, but I've seen several nice rifles sell for less than $1000 with Imbel receivers.
Needless to say, you have a lot of good options. It's just a matter of what YOU are interested in.