One of my all time favorite nurseries, Arnold's Greenhouse, is in Kansas. It's somewhat "right of center", near the little town of Le Roy about 30 miles southeast of Emporia, but perhaps close enough?
As for iris in particular, I'd imagine my conditions are fairly similar to yours and I've have never had any issues with irises that were acquired from from growers in Oregon or California. It's possible that where an iris was hybridized might matter, but not so much where you buy it from. For example, Barbara Nicodemus is a hybridizer from Missouri and her irises have always grown exceptionally well for me, but I bought many of them through Joe Ghio in California.
