Just have to keep you're eye out. Unfortunately the hobby isn't as varied as it used to be. (IE everything is ball pythons now) So people actually producing the "miscellaneous" snakes are a lot more rare. Keep some money to the side and be ready to pounce when the babies start hitting faunaclassifieds and kingsnake.
Yeah! I don't know if it has to do with specific russian rat snake breeding periods, but it seems like everyone's having young snakes available mid-summer for some reason. I've got my money right here! They seem like they're bought so fast.