Ruger 10/22.

Out of the box it makes a good, accurate semi-auto plinker.

With a few mods, it can be a tack driving target rifle.

If you're talking centerfire, you'd be describing an AR-15, which you can't really get in for under $700+ these days. Prices on them are through the roof because of BHO in the White House and the fear of another ban. Panic buying and price gouging are the norm.