Not "lot of image files". Let us say we have an animated dog. I want his walk animation cycle which might be 10 to 15 frames. A bird flying, again 10 to 20 frames. You get the picture ?
"Big money" ? Nope, I am looking for assets for some projects of mine to be done using an engine called LibGDX.
Here is an example right here on SL market place
This seller is selling an animated deer.
https://marketplace.secondlife.com/p/Animated-Running-Deer/2478738
And he also has rendered it into a GIF animation