I don't know where you are located or where you are having your baby, but I can tell you that you surely need to talk to a nursing/lactation consultant soon after you deliver, if not before, and she can give you your best options. I can't tell you how important it is that you talk to one: I came from a family of nursers and have several friends that do too but nothing beats the info and assurance given by a pro, believe me! They offer all sorts of tips, including what pumps to use, buy, rent, etc.
Often, you can rent a commercial pump (the absolute best for establishing your milk supply) directly from the hosp. you delivered and then the lactation consultant can help you in finding a good pump that is best for you and in your price range. I rec. Medela, but like others say, they are expensive and others may work fine for what you need. FYI though, Medelas are very good and very easy to find and buy supplies, replacement parts, ect. for and they don't change model parts often, so you don't have probs. finding repair stuff.
Also, FYI, I had my baby in a rural hosp. where nursing consultants were not available, so I found out that Harris Hosp. in Ft. Worth has a WONDERFUL nursing center on the ground floor full of products, info and consultants. You can call and talk to them for free (anmdn they have a 1-800 #) or just walk in the shop and talk to them for free. However, you must pay if you make a private opt and if you have any probs, I would highly suggest this. Many insurances cover it just the same as a dr. appt, but mine did not-just another source for you. And they have all the medela pumps there for purchase (though you might find cheaper elsewhere) and out for you to look at and examine.
Hope I helped and best luck! I found nursing very easy once established and much more conv. than worrying about bottles and much cheaper! Hope it is as great for you!
Best of luck!
T.