Another vote for the Avent cups - I think they recommend only using each cup 5 times but I am sure they would last longer if you are not sterilising every time (as it's no longer recommended). I write the date on in pencil then cross it off each time I write the new one (rather than rubbing off), so that I can keep track of how many times I've used it. I think after about 10 times I'll probably recycle them and buy new ones. You can use the lids an unlimited amount of time though, which is why you can buy just the replacement cups on their own