I think it does not hold to adjust pricing by the time an artist required to create the asset.
10 hours for a terrain like , if the workflow is established, is simply far too long. If everything is set and the workflow is ready to fire, is one hour max including all progress bar times.
Sure, you might have done lots of revisions here and there to adjust it to your liking and thrown it over a few times and fell in love with it, but would be individual taste stretching it to 10hours.
But I agree with the overall consens - either buy or do not buy, and no one is forced to buying.
, i would look forward to see on the marketplace for a good price. If shows up on the marketplace for the price you mention, then the argument here is instantly over.