For your price range the Mosin rifle is a great buy and probably your best bet.
You may be able to find them a bit cheaper but it is worth a little extra to be able to pick through and also support your local dealer. The 7.62/54 is an excellent round and still in use as a sniper weapon. It is the cheapest centrefire rifle round. You can get cool repro scopes and bases for a cool soviet Sniper repro. If you liked Shooter(I loved it) check out "Enemy at the Gates".

A mauser is another good choice but more money. The best buy in mausers would be a post WW2 east german model. They are the same excellent rifle as the earlier WW2 ones but not as expensive. The Israili versions are in .308 but some are more accurate than others.

Milsurps rule and will probably go up in value.

Some people hate them but I like the NEF Handirifle in .223 as a plinker and Varmint rifle. Add Walmarts finest optics and you have an accurate rifle that takes military surplus cartridges and very close to your budget. If you want to improve your skills this is a good choice. By the time you are getting good enough to need a better rifle you will either be sick of accurate shooting or want a really nice rifle.

If you get the Mosin the longer rifle is a better choice for accuracy(and recoil) but those carbines are so cool. Huge cartridge ,light short rifle with a steel butt pad makes for a hard kick.