Well, in all cases so far I have not been the originator of the models. Simple shapes are about the limit of my abilities in that realm, and I barely have time as it is. They were either freebies of the net, or I bought them. I haven't done too much of the latter, since it does get expensive quick, but that dragon model was one of the ones that I had to purchase. I think it might have been on sale at the time, but I just looked up the current price for you and it's $34.95 American.
It's called Adult Hatchling Dragon and it's on the DAZ Studio site if you want to bother with all that. Someone else used it in some animations that I think are still lurking about the Artist Gallery here.