We ran and rebuilt Walkers and Lincolns on our tow rigs for decades... If it needs a pump kit, you may as well redo the ram at the same time, check the check valves, etc... Also check the pin and caster wear... Casters used to give us grief, once the pump needed rebuilding, usually so did the wheels... The other thing is the frame - they can tweak or warp, and then your jack needs serious help (we used to reinforce them because of that - made them heavy, but they took a beating)...
You can get a new one for 3 bills, going into it blind on the above issues, I'd say $50. If ALL it needs is a pump kit and nothing else, then probably twice that, knowing it's been abused enough to need pump work.
