I don't know your location in TN but you could try Wild Irish Rows in Springfield or Rockytop in Eagleville. No really reliable dealer is necessarily cheap, but these people are established. You usually get what you pay for and so-called bargain irises, like those in the marts, are often not labeled correctly.

Most major mail-order dealers have extensive web sites with photos.

Currently I'm buying a lot from Mid-America, But I'm fond of Cooley's and Suttons as well.