I know this is probably going to sound really weird, but I would definitely buy credits to get something like this.

Make an item that when you use it, it permanently gives you 1 extra hatch per day (no matter what clas.s you are). To make it fair though, only allow each user to activate a maximum of say 3 of these.

So if you're a rancher you can use up to 3 of these and be able to hatch up to 6 creatu per day. And if you're a merchant you can also use up to 3 of these and  be able to hatch up to 4 creatu per day.

It could be called something like a 'hatchery extension' or 'hatch ticket'.