Osatia seems to be broken and will not sell the custom mats any more.
The mat-maker Osatia says, "I can sell you a mat just the way you want it. Are you interested? It'll be just how you like, and only cost 500 gold."
You should SAY YES if you would like to have a personalized mat created by Osatia.
You have completed the quest named 'Help the Mat Maker'!
You say, "Yes."
I get nothing in response to this. It makes me sad.