PLEASE HELP - Breast Pump needed

Okay, I am at my wit's end here!!! If anyone knows where I can borrow a good breast pump, or knows someone selling one for a reasonable price PLEASE LET ME KNOW!!!! The twins are doing decent on their feedings, but they have to have formula because I can't get enough milk, and the formula is very hard for them to digest. The pump I use at the hospital works great, but with Chad's job situation it is beyond our means to rent one or invest in a brand new one. I was given an inexpensive pump, but it doesn't work very well and won't maintain suction long enough for me to get anything. I talked to the lactation consultant and told her everything I was doing - pumping every three hours, warm compresses, drinking fluids, etc... (I did nurse/pump successfully with Selah so it's not like I don't know all the tricks.) She said my problem is definitely the pump, and to try to find one at least like the Medela Pump in Style, which is what I used last time. I really hope one of you can help me find one - I am so frustrated right now knowing one of the few things I can do to help my babies is being hindered by something like this!!!!!! Thanks so much for your help. My babies' tummies (and health) will thank you!!!!