Wouldnt have thought storing your jetski in the garden would be an issue, storing one at the marina would cost an arm and a leg, but then again if your renting a villa on the palm, maybe thats small change compared to us lower classes in springs ;-)
A lot of guys launch their jetskis at the small harbour just past the burj al arab off jumeriah beach road, think the cost is fairly cheap, and if you bring a level of sanity and consideration to the guys down there it could be a win win.