J.L.
I rented mine from Optimum Wellness:
http://www.optimumwellnessllc.com/index_files/Page435.htm
You can also rent from Village Maternity in University Village:
http://www.villagematernity.com/pump_rental.html
See if your doctor will prescribe a breast pump for you -- you can then bill it to insurance. I'm not sure how often that happens, though. I was only able to do it since my daughter was premature and in the hospital for an extended period of time.
It looks like the pumps available at these places are "hospital grade" -- they are much better than the kind you can purchase at a store. So, they are much more expensive. Depending on how long you need to pump, it may be more economical to purchase a retail grade one for yourself.
Lastly, I found a page that lists a bunch of different places that do rentals:
http://www.breast-friends.org/pages/breastpumps.html
Not sure that either of these will be any different than the two I mentioned, but it's worth a look.
Happy pumping!!