It's times like this I wish I was currently in the rat business! Haha, my old regular customers wish it even more than I do.
I miss the business and look forward to getting back into it one day, but my current lifestyle isn't at all compatible with being tied to rodent colonies.
If you're really good at breeding rodents, it's a great business. If you're about average you might break even. Most people give up within a year of setting up and most of the rest give up in their second year, hoping it will be better than the first, but it usually isn't. I'm certainly not trying to put anyone off doing it - I'm currently a buyer of rodents not a supplier, and don't expect to be a supplier again for the best part of 10 years, so by all means, everyone, set up some successful rodent farms ASAP! Haha.
But, the reality is that for most people it's not worth it unless they either enjoy it and don't mind spending a lot of time, or they're very talented at doing it well and quickly and they're able to maintain a very consistently high level of dedication to the colony; it only takes a brief period of neglect to destroy your colony, and if you have a colony disaster it takes the best part of a year to get the colony back to full output. Even ignoring disaster events, you need a very keen eye for picking problems and nipping them in the bud, and good management skills keep planning a life cycle ahead so your colony will always be at the right size and age structure at all times of the year, or alternatively you need a lot of freezers which you know you can rely on. If you just put in a lot of consistent time and work you can certainly make more money worth of rodent than the hard expenses you put in, but if you value your time at more than a few dollars per hour you'll be squandering it. Most of the small and medium suppliers make reasonable financial returns on their small businesses until you consider the number of hours they spend and the fact that they have a stinky rat shed on their property and can't ever leave the colony unattended and they're still making under $10 per hour.
But, if you know how to run a colony very efficiently, you can definitely pump that up to more than $50/hour, and if you enjoy it that makes it even better. It's all about managing it efficiently (or loving it and not caring that you're making low $/hour as long as you're making money while enjoying it).
Most people who start up small rodent farms do it during peak demand season around this time of year when they lament paying high prices, which means they get to full output around the time of the year when supply is highest and demand is around the lowest, then they have a colony disaster event around the start of the high demand season when the first heat wave of the year comes and they don't know how to manage it, which is where most of them give up and go back to being buyers after a costly and heartbreaking experience. I can't count how many times I've seen different people making the exact same mistakes, or how many operations I've seen where people just don't know how to manage the animals. Once someone gets out of the market for whatever reason, the whole system ends up with a supply shortage/price jump and it's unpleasant for everyone other than the remaining suppliers (I must admit, I loved those reasons when I was a supplier, haha!).