I'm about to bed (hello 3 am), so I can't argue for long, but my point still stands. It's not a simple command - it probably takes the same amount of work to make, in order to make sure the conversion goes well. (If it didn't? Jaggies and horrific quality would be rampant.) If it does, then it should cost the same.
Of course, you see it differently, and that's fine.
...
In fact, I decided to quickly do a simple resize, to see how much touch-up it would need. Base legs, just with the regular Photoshop resize.
(Why the legs? Because that's a huge difference in Paw and Human legs.)
So, at least for this item, it was a fresh pixel-ing. I'd check for the others, but I don't feel like that much effort. So, basically, I feel it is just to ask for the same amount of pay for practically the same amount of work.
Also,
their job is to make items to sell. It would be like asking a professional web designer to charge a smaller hourly rate for a mobile-only website. That's now how it works.