Not many who are known to breed them, but you do get the odd Thamno-freak with a litter here and there. Jonathan Crowe is the "biggest" breeder of garters I know. Seems like he almost always has a couple of babies kickin around.
Nice choice in morphs! I like the Iowa's as well as the Nebraska strains. Myself, I'm not a morph person. More fun playing with different species than the same one with different looks. But that's just me!
Either way, it's great to see another Garter-Freak in Canada. All the best in finding your starter stock.