Some well known hybridizers-

Here is a link that might be useful: Joe Pie Weeds Garden

A very favorite place of mine to buy-

Here is a link that might be useful: Ensata Iris

a great pleace for perennials and siberian iris.

Here is a link that might be useful: Fildstone Gardens

This is a great place, sending top quality plants. Highly recommended.

Here is a link that might be useful: Snowpeak Iris for Siberians and other kinds.

I bought some from Joe Pye Weed's garden. They were fairly small, but are growing vigorously after direct planting.

The customer service was excellent.