ok... lots say it's easy but probably because they can't remember when they started up. There are heaps of threads if you do a search on breeding rodents. Yes it's relatively easy to set up and breed mice, it's a little more involved with rats. Heaps of people use different types of tubs or cages to breed with. Over time you'll find what works for you over other methods.
Personally, I have found it takes a while to establish good breeding stock. Rodents can be horrible creatures, killing each others young and each other. I have had dominant females destroy whole litters and some that just chew off their tails. I kill any who bite me, nice mice get along better and breed better. Rats are more difficult because they let their environment affect them. They don't like disturbances and very loud noise, they also eat a LOT. I had one trio never breed because a cat 2 doors down use to get in and sit on the roof of their cage. Also consider the costs. If you only have a couple of snakes and can get away with mice for now I'd just stick with them. Or maybe get together with someone and swap frozen goodies.
I have 7 snakes and breed both rats and mice but it's not because I want to. I do not have a constant local supply, mice are not available at all and the local prices are freakin insane. If I could find constant local supply, of exceptional quality I would not be breeding vermin at all.
I also give my excess to the local wildlife carers
sounds like theres alot more involved than just chuckin a couple a rats in a box with water and food lol.
