Here's some pics of a Home made Hydro Pump.
I picked this up in Himley Hall a few years back.
Simple, but very effective.
Only drawback is it doesn't suck.
Aye, It's a bit of a beast. Just a tad over-engineered.
As you pointed out Mark, it does need a few refills for a complete pump up, but for £12 and 2 gallons of fluid thrown in the pump was basically free.