Did I hear someone say you are in BC Canada? Where abouts?
Anyway, I have a fair bit of experience with keeping garter snakes <even though I know it is illegal, blah dee blah blah! lol>
The thing with Garter snakes is that they need LOTS of room compared to other snakes, and they definitely thrive on a diet of small fish, guppies or baby swordtails when young, feeder goldfish when older, both of which are easily attainable at local petshops. If you are in BC I can even tell ya which pet shops.
Anyway that cricket thing is a load of malarkey. It is soooooooo hard to get them to accept crickets. Another fool-proof food I have found is tadpoles and frogs. Unfortunately though, they would have to be from tree frogs as all but the very smallest bullfrog tadpoles would not do.
As far as other alternate foods you can try earthworms, dew worms, and BROWN <not those plentiful black> slugs. I have heard of many snakes doing really really well with the dew worms. Feedings should be a little more frequent than with your average snake. I find at least every three days is best.
Now for space. Even thigh they are very small these guys need lots of room. For instance I wouldn't house a young adult or an adult in anything smaller than about 4' long for any length of time. Babies of course could go in say, a 20 gallon aquarium. You need to have lots of natural hiding places and a very large water bowl big enough for the snake to swim in, not just soak. I have found using the eco earth or coconut dirt with a nice thick fluffy layer of moss on it works well for substrate but of course going with the nice natural viv is much harder to clean when cleaning day comes!
With these guys I find that the full spectrum lighting and very low heats in your warm areas < 80 - 85 degrees> are best as far as lighting needs.
Anyway if you need more info. PM me if you want. I definitely feel that a garter snake taken care of properly in captivity will thrive if given the chance. Another super cool thing is that if you are lucky enough and find a female around late spring in a little while you will likely be surprised with lots and lots of babies! They have live babies and its so cool to see them born!
Rebecca