My thought would be a 98k mauser, in .308. I have a WWII era cz made mauser, that was converted to .308 post war. It only ran a couple hundred bucks or so.
I know that mitchell arms is currently selling practically brand new mausers. I am reading their ad right now.
service grade mauser for 250 bucks. good service condition cleaned and inspected.
collector grade for 399 smackers.
then again, how about an enfield? 10 round detachable box mag, very powerful, very cheap. They float around the shops here in the $200 range.