Just like the stuff in hospitals, this gel which evaporates on contact, requires no water and kills 99.99% of bacteria.
You'd be very hard-pressed to get this quantity for this price. It lasts AGES too! I expect a 500ml bottle to last me all year as you only need a tiny amount.
It cost's about £1.30 in ASDA for 100ml - that's their cheapest too, some are £1.40 for 50ml.