agree with starlover - they are not cheap and you need to make sure that BF is for you before you invest as shops won't take them back. You can always dispatch dh/dp to the shops once you have sussed it or buy online.
I was advised off a manual pump by a friend who said she almost got RSI as she was pumping so much! Used the medela mini electric one myself which was OK but very noisy. Think they all may be noisy though. Incidentally, you can rent them which may be a better bet, depending on how much expressing you end up doing, whether you want a double one etc etc