9 months on T and pumping about every other day has got me to 1.5 inches soft and up to 3 inches hard.
The cheapest pump you can make is out of a 60cc Catheter Syringe. On amazon I ordered 10 of them with shipping it cost about 12 bucks. I got a bunch of them in case I messed up cutting the pointy end off.
Basically there are two ways to use them. (1) Cut off pointing end, insert dick, pull plunger out slowly. or (2) Take plunger out, use a hose from a "normal" penis pump but attach it to the smaller cylinder from the syringe. This method uses parts from a cheap pump available at most adult stores.
I can tell you that regular pumping does help size. I'm not saying it will give you permanent growth, but it will increase the average size your erection achieves even when that erection is not caused by pumping.
PS: Use lube every time you pump. Your dick will thank you