Do cheap breast pumps effect how much you can pump?

I see how much some of you are pumping and it's so discouraging. I have a pump that I bought for like $75, (I know you can get them from insurance, I didn't, long story) not super cheap but the cheapest one they had at Target. The most I can pump is 4 oz in the morning, after that it's only 1-2 ounces every few hours. I've taken every supplement I can. I can't figure out the problem, starting to wonder if it's because of the pump? Just getting discouraged because on the breast my baby feeds for about 45 mins and it's killing me, I'd much rather give her a bottle but I can't produce enough. I'm almost ready to switch to formula at this point.