Spline wrenches are cool because you can turn a variety of different fastener heads such as hex, partially rounded hex, 12pt, square, external Torx, and yes, even spline heads, with one wrench. If you’re willing to give up the ratcheting feature in the Stanley Proto and SK spline wrenches, you can get a set of seven Craftsman combo open end/box spline wrenches from Sears for under $20.
Craftsman angles the wrench heads by 15° to save your knuckles and they reinforce the open end so the wrench doesn’t deform under high torque, rounding the head. The set normally includes 5/16″, 3/8″, 7/16″, 1/2″, 9/16″, and 11/16″ wrenches, but to be nice Sears is throwing in a 5/8″ wrench and a storage tray.
Universal Wrench Set [Sears]