My spouse and I both have histories hauntingly similar to Jayden's, and taking this approach, albeit learning many caveats to it along the way (eg. artwork on commission is best handled immediately, and with thick oven mitts), we've done decently for ourselves.
If he doesn't struggle with focus for autism-related reasons like we did (or has -guidance- in that struggle), and his family continues to support his artwork without the background hum of 'when is he going to make real money off that' that I've heard all too often in families with a developmentally disabled child, he'll go far.
Perhaps even a "counter"/queue/approximate ETA (the ETA can be manipulated to show 30% more so there is no pressure)
Thus the $40 is x4 the $10..
One thing I completely failed to consider is that Jayden joins this event(s) not for the income but for the participation, the sense of belonging and not being isolated. If he stays home making figurines 24/7 then that beats the purpose, and it's something I definitely did not aim for with my idea.