I'm an OB nurse, and regarding using a used breast pump, here is some info you need to know. All Ameda pumps can be used by multiple users if you buy new tubing. They are a "closed system" so milk cannot back up into the pump itself and then be recirculated. Only "hospital grade" Medela pumps are closed system. By hospital grade I mean the Classic, the Lactina, and the Symphony, all very expensive pumps that people usualy rent. The Pump in Style, while an excellent pump, is not a "closed system" pump, so theoretically milk particles could back up into the pump itself and then be recirculated. So while I don't categorically advise against using someone else's pump, I PERSONALLY wouldn't use someone's pump who I didn't mind their milk possibly being fed to my baby. Like, if I had a good friend or a sister, I would feel comfortable, but definitely not a stranger from Ebay. For what it's worth. And this is not a plug for Ameda because I used Medela myself. Both are excellent pumps.