Hi, I've purchased some at a local Asian grocery store. I planted them before the end of Winter. The squirrels found them delicious, apparently. I'm hoping at least a few of the remaining ones sprout.
organicturmeric.com is a source I can vouch for. It is an organic farm local to me, specializing in multiple varieties of turmeric and ginger. I do volunteer work there sometimes and the quality is excellent, I currently have seed turmeric and ginger from them planted, waiting to sprout.
Don't judge each day by the harvest you reap, but by the seeds that you sow.