22 Luger? Erma or Stoeger? Either way, parts are hard to come by. Maybe $150-$200 if they are in working condition, but no more than that.
9mm barrels for Lugers are available from Numrich. You will spend about $300-$400 to get it rebarreled, and it will ruin any collector's value, but it sounds like it's already a shooter or project gun. Either way, $600 is a bit steep since it needs work, you should pass if you can't get it pretty cheap.