We recently got a child and needed to rent a breast-pump for a while. the pump was absolutely fantastic and made life soooo much easier (for my wife; now I could also feed the baby at night). However, after a month or so we had to give the pump back. ...and looking at the purchase prices for the same pump nearly gave us heart attacks. Here is a dirt simple replacement for the really expensive part of the medela lactina and lactina select pumps. You will still need to buy the actual piston set (the yellow plastic things), but those are quite affordable in comparison to the actual pump. For this thing you will also need a small geard electric motor with approx 50-60 rpm, a speed regulator and a fitting power supply. I used a 'PGM-37DC12/77' motor from pollin.de with a regulator '919D2P' from conrad.de and an old 12v power supply I had lying around. The pump works fine and, according to my wife, works better is more agreeable than the original medela pump (but take her criticism of my work with a grain of salt). I hope it helps someone else out there save a couple of hundred euros! Warning: contrary to the original this thing will quite painfully pinch your fingers if your are not careful!print out the parts, get a suitable motor, regulator and power supply. You will also need 3 inline skate bearings, some 8mm dowels and one 8mm bolt and nuts as well as some 3mm bolts and nuts (for the lever-arm) assembly should be quite stright forward (see picture). If your motor is too weak to fully lift the pump-plunger, you can add weights to the lever-arm; that should help even the load for the motor. (and I also love to use hot-glue to fix things and insulate electrical connections)