This is the back brace I use, I ordered it off Amazon for $12. It doesn't relieve all discomfort, but it most definitely helps and supports my belly.

I have one that straps around the bottom of my belly then the back part velcros onto it and gives lots of back support and another strap comes over the top of the belly. In the pic on amazon it looks very uncomfortable but is actually awesome. The only downfall is trying to bend a lot at work but I love it. I believe I saw the same one at motherhood maternity but it is half the price on amazon. I just searched belly bands on amazon and they have a huge selection. I bought three so far because I'm having twins and I wasn't sure how I would like each one but my favorite is the one that has the three straps