Secondhand cocker or Impy
Why not get a used cocker or impulse. Make sure the gun gun isn't really old and worn. Look at the exterior some scratches are ok but it should look decent. See if the bolt housing is smooth. Unless its running a delrin bolt (plastic) this should be a good indicator on lubrication and amount of use from the owner. TRY the gun. Does it shoot straight and have a nice snappy sound (not letting all the air out in a few shots)
Investing a little in a gun now is smart. Don't get a Kingmann Spyder, because the finish and quality is not the same as with the markers mentioned above. Second of all once you try one of the nicer guns you'll know. Go ask, to try some!