Hydrangeas Plus and Wilkerson Mill Gardens are probably the two biggest mail order sources but other places like Forest Farm, Rare Find, Joy Creek and Plant Delights also offer excellent selections.

Also, many participants to this forum seem to have excellent success finding hydrangeas at local outlets like Home Depot and Lowe's. In season, of course!!

This should give me a nice start--thank you!

Be aware that most establishments, including online ones, may have a limited supply of hydrangeas at this time of the year. As soon as they stock up, you should see more variety. The locals will get stock up depending of weather in your area; usually May for me. The online ones sometimes tend to advertise by email and can sometimes notify if/when a specific variety comes in. You have to obviously give them your email address somehow. Hydrangeas Plus has a way to give them your email for seasonal emails in their website.

I've gotten some hydrangeas from Bluestone Perennials that have grown fairly well (smaller than Wilkerson Mill though but a little less money). eBay sells a ton but beware of the low prices - they are usually very small starter plants so must be babied for a year or two.

I'd forgotten about Bluestone--they do have good products.