300 is a tough budget for board and bindings new. The board is definitely too small for you, but short boards like that don't have the best resale value. I'd hold on to the bindings if they fit and put that full $300 towards a new board.
K2 Raygun is a slam dunk for just over 300 new for a 2014, but you may find last years model for $200-300.
Or get this in a 154 wide if your more park oriented, 157 if you the all mountain kind of guy and that should leave you some cash for bindings.
Rome Garage Rocker Wide Snowboard 2013 | evo outlet