I've bred feeder mice twice and it's definitely something you need to upkeep daily as far as cleanliness goes. As people have said, yes, mice do stink and their bedding will contribute to it over the days (depending what bedding you use), so if you have the free time in your daily life to do this... you're going to have to clean their husbandry constantly and keep up with it. Out of breeding your own feeders I would say this is the most time consuming, because they are constantly making a mess of their feces, making a mess of their food, etc. If you're on top of cleaning, there shouldn't be a problem at all regarding smell and uncleanliness.

I kept them in a standard tub I found at Walmart (I don't remember the dimensions but it was wide enough to give them some roaming room, and high enough so it wasn't claustrophobic for them). Hooked their water bottle to the side, kept a fresh dish of food for them to munch on, a little mouse igloo to sleep in, and a wheel to keep them active. Had two females and one male to start (since it was my first time), and they were fairly simple to take care of.

It's also an upkeep to keep them happy and healthy. They're going to need a constant supply of food and fresh water, as well as an area of the household/garage where there is no disturbances (just for the sake of not stressing the pregnant females out; I'm not sure if constant disturbances stress them, but I kept them in a quiet area so they're content).

True, it's easy to get attached to your first litter once they're born, but during my time of breeding it certainly saved me some bucks from running to the exotic pet store to pick some up for $1-$2 a pop. It's definitely a learning experience for every snake owner to try, so I would say give it a shot and see how it works for you. I would do your research on it first just to get all the necessary supplies, and there's a wealth of information on here you can gather to do it if you really want to pursue it.