I brought a maternity support belt, that was across the back and stomache, was £35 from mothercare.
However i only used it once, was awkward to bend down or sit down in.
I mentioned it to my physio, who i go to for pelvic girdle pain, and she said support belts are not designed for sitting in, and if you sit down alot then its uncomfortable and not practical.
She did say "tubi-grip" was better. This is the exact same as a bandage that goes double over your stomach, i got it off the physio, not sure if you can buy it.
However that didnt suit me either, as i found it uncomfortable and felt like someone was sat on my stomach, and gave me abit of pain in my tummy.
I know ebay sell alot of the support belts i have, altho they are second hand, they may be worth a try to see how you get on with it before you go and buy a costly one.