If you're getting into pump from semi play and already have an HPA tank, or potentially barrel kit and hopper, a Sniper (pump autococker) could be pretty convenient to transition to. There are definitely lower end used snipers in your price range here and on MCarterBrown as well as eBay.
If this is really just the gateway yo pump and don't need modularity/upgrade ability, you could potentially look into older markers like the ACI Maverick/the original PMI Trracer. These would be a much cheaper way to see if you actually enjoy pump play. I just snagged a Trracer package on eBay for $50 shipped as a loaner gun and backup to my Phantom and Sniper.
Just looking to play some paintball.