Uh, hello, professional animator here. It absolutely does cost money to make more animations in a professional setting beyond the cost of the software. I think you're forgetting something very important here: time. The time an animator spends making that new animation, and making sure it hooks up with other animations properly, is not free.
And a well done quadruped locomotion cycle, even if it's just a vanilla walk, certainly takes more than 45-60 minutes. Not counting the time spent researching the correct gaits of the animals in question (it's not always easy to find good references for a specific animal at a framerate you can use, with a clear view of what is going on) it's going to take at least a few hours to get that cycle completely polished. This assuming you have free reign of the work and are not expected to start with keyframes, run those by the art director, go to breakdowns, show those to the art director, go to inbetweens, again show those to the art director, and final polish. And all of this again, making sure the cycles work with the other animations they need to hook up with.
And as for fixing existing animations; if it's going to be a big change, that means it's not just 'fixing a run cycle', it's fixing that cycle, and any other animations that connect to that cycle, since the poses are now all changed.
I don't think you understand how tedious and time consuming this can be on a professional level.
And don't get me started on rigging.
