You could just get one like mine :-)
http://ecomodder.com/forum/showthrea...tern-2624.html
Seriously the cheapest thing would be blue plastic food barrels, you can typically find them for free/ cheap.
A RV water pump works great to pressurize your home; or if you are cheap like me you can buy a shallow well pump + pressure tank @ Harbor Freight on sale for $69.