Are you a HIPS member ? I can't remember if you said you were, or not
. Anyway, just a "I'm looking for....." thread on ANY of the forums , is a good starting place. A general "google" search sometimes comes up with a source (commercial) that you hadn't thought of. If you check the AIS wiki, and look at the photographs .....the "copyrighter" can sometimes be contacted, for help in finding an iris, as well.....i.e. the person who took the picture at least SAW the iris, somewhere.
If you ARE a HIPS member, there is the "Commercial Source" list, and , sometimes....even if a vendor no longer lists an iris....they may STILL have it, just not as a "salable" one. Watching the HIPS Rhizome Sale listings, or The Pickle Barrel Iris Sale Listings can turn up some really scarce cultivars, as well as almost ANY of the "fund raising" sales held by local iris groups. There are also some good results, at times, from just ASKING your vendor, when you place an order, " I'm looking for "XYZ", and I know you don't list it, but is it possible you have it in your private collection ? Or do you know someone who MIGHT have it ? I've gotten some great leads, and some great iris, that way.
And, don't forget to keep your eyes open at "bloom time " ! I've found some real "dandies" just driving down the street...........if it looks like what "XYZ" is supposed to look like.....stop, knock on the door....ask them what they know about the iris.........finding iris this way USUALLY results in finding a new "iris buddy", as well
! Good luck with your search!