No need to pay a fortune, I found a drinks can chiller in a pound shop, big enough to hold four 330ml cans, this is big enough for a small freezer pack and all my insulin requirements etc, I work and travel to Madrid and back every month and this works perfectly, or is it I'm just to mean to spend (waste?) ££££££'s. It also has the benefit that it looks medical, it is white, and even Ryan air have never argued about allowing it aboard, in addition to my normal cabin allowance.