"Only used twice!" "In like-new condition!!" "Great deal - 75% off!"
It's tempting to want to save money by buying used - I love a good deal as much as the next mom- but don't do it! There are only 2 things you should never ever buy used for your baby - car seats and breast pumps. Nearly all consumer grade pumps (i.e. all of those except hospital rentals) are single user medical products. Sharing a pump with another woman (or buying used) subjects your baby to a small but very real risk of contracting a serious illness, like HIV, Hepatitis B, HTLV-1 and Candidiasis (thrush), to name a few. A good rule to live by:
If you wouldn't let a woman you don't know nurse your baby, don't use her breast pump!!