I breast fed both of my children for the first year of their life. My eldest had no issues to write home about, when it came to feeding. If there was the smell of milk in the air, she'd start sucking. My youngest, on the other had, her mouth was too small and she was too impatient for us to get the breast feeding down.
As such, I had to purchase a pump, to relieve engorgement, and make sure that she got enough milk. I ran to Target, near my house, and picked up the Avent Isis manual pump, as I had heard from my lactation consultant at the hospital that it was a good one.
It did the job perfectly! And, I loved the fact that I could pump directly into an Avent bottle, considering that Avent was my first choice of bottle, if I had to use one.
I later bought a Medela electric breast pump, but I have to say, the Avent worked much better and was much more comfortable. The difference was really in whether or not I wanted the work out it would give my hand to pump manually.
As a warning, the plastic in the pump, I have heard, contains BPA (which most plastics and glass contain). BPA has been concluded to be toxic, though I didn't know that at the time I was pumping and/or feeding my children out of a baby food glass jar. So, it may be something you want to look into.
If you need to pump, I highly recommend this. It is comfortable, it's easy to use, it's easy to clean, it comes with all kinds of accessories, it's a great deal, it contains their patented cushion to mimic babies natural milking action, it gets just as much milk as an electric pump (as long as you're using it correctly)...
As a tip, in order to mimic baby as well as possible, and get as much milk as possible, start with short fast pumps, and then move to slow long pumps, once you see that there's milk coming out.