Yeah, the thrilling world of breast pumps.
A couple of hints, get whatever one you fancy online, or if at a store, check the return policy, this could be a good purchase to make at Walmart. Certainly not at Babies R US, because they won't accept a return or exchange, even on a broken unit unless it is new, unused and sealed in the box.
We went with the cheap and cheerful "The First Years" by the Learning Curve. The natural Deluxe single breast pump. It worked pretty well for a month, before dying. This is where the company came good, kind of. The website FAQ is junk, and emailing them for help is a waste of time, call them up, and they are pretty helpful, we had to send the unit with all the parts back, including a copy of the birth certificate because we lost the receipt and they'll send us a replacement unit. Apparently from talking to the person on the phone, our unit was funky from the get go. We still have to pay postage to send it to them though which is a shame.
One thing they don't tell you about, all these electric breast pumps sound like a belt sander, really scary stuff, but they work quite well. I'd recommend a double pump though because it's a slow process and you might as well do both sides at once if you can.
So over all, $50, can't complain to much, it does the job, it was cheap, it's easy to clean and use. I wouldn't want a hand pump though, that would get tedious fast and I'm not sure why some of the other pumps cost $300 or so, a tad pricey, cheaper than renting in the long run though.