Not very hard.
https://www.kijiji.ca/b-reptiles-amphibians/canada/isopods/k0c14654004l0
https://www.kijiji.ca/v-pets-other-...ch/1445242062?enableSearchNavigationFlag=true
That took about 5 secs.
Ya, if you think your going to walk into a Pet Store and get Isopods, Sticks, Mantids, ect, you will find nothing. The same is true in the US. You need to look online, and join some CA Facebook groups. You can find what your looking for, you just need to look in the right places.
You can also catch native snail's, sticks, fruit beetles, ect, and breed them out into feeders. You can get those from local Facebook sale groups. Ask, and someone will have some infesting their garden they would love to get rid of.
I gaurntee you can get roaches the same way, from Facebook groups for reptiles. If you really want them, they are there, you just have to get in the nitty gritty.
We have 2 pet stores in my town, and before I gave them crap for weeks for not carrying roaches, now they have dubias (the mom and pop one). Most petstores don't care to carry roaches, sticks, Mantids, Isopods, ect.