It depends on where you live. I am in Columbus, Ohio, USA and I was getting them at a latino grocery store here, but then I found them cheaper at an african market. go anywhere immigrants tend to go, like asian markets or specialty stores. I have a customer who owns a chain of pager & cell phone stores, and he sells them. Check the rates, though, they vary widely. there also is a trade off between price and quality. e-mail me and I will give you more specific info on brands.