Jimi,
Remember that all garters are native to North and Central America. Shorthead garters aren't very common in the pet trade, but part of the fun (for me at least) is to scheme about ways to get which garters I want. Do I know anybody from their native range, or could I plan a herping trip there for any other reason? Another member of this forum (Daniel) has created a program called SnakeFinder. It shows the home ranges for each of the species/subspecies. Have a look (
snakefinder).
Rick