Coast Garters are pretty much endemic to California. For this reason they are not widely available (like Santa Cruz, Diablo Range, Sierra Garters, etc.). They can be quite common in the right habitat and are highly variable. Here are a few I found while vacationing in California last month:

Example like the one originally posted:


"Low Red" Coast Garter:



"Checkerboard" version - I found 5 of these in 20 minutes in a very public place:




I also found a pair of Santa Cruz Garters, here's the female:



The male wasn't too thrilled about being caught:



And last, but not least, although "beat up," this Diablo Range Garter was a nice find:



All snakes were photographed and released at their point of capture.