For the trolley - a few barrels from a car wash place, a cheap trolley from Maplins or similar, 12v pump from ebay (£20 or less), tubing from a plumbers or B & Q, etc, jubilee clips, a few bits of wood, bunge cords, cable ties, etc, 10amp 12v battery, some wire, a switch, etc, and make your own.
Most of the stuff needed can also be bought on ebay real cheap.
Total cost £120 or less and you can make it to suit your own needs or change it as needed.