Re: Best pump for increasing supply.
You could rent a hospital grade pump. Depending on why you are having to pump, your health insurance company might cover the rental. If exclusively pumping though be warned that your milk supply might drop. Mine had dropped down to 1/2 ounce per pumping.
I'm still pumping every 2 to 3 hours and every 4 overnight. It was recommended that I use herbs to increase my milk supply. I've been using Breastea from http://www.breastea.com and I'm back up to 4 to 5 ounces per pumping now.