With either of these options (well, any animal purchase, really) a lot of research on the seller is a good idea. I don't know about ball pythons specifically, but MM has more listings with incorrect IDs on other snake species than I'm comfortable recommending a novice keeper try to catch. Some are honest mistakes (that the sellers correct when informed, if they are informed) and some are clear and certain deception for profit that sellers block messages regarding. I've not seen any of this come up in seller reviews there, so buyer beware.
Reptile expos are...interesting, having been on the other side of the table for a while.
With both these options, a breeder focusing specifically or primarily on your species of choice is typically a better bet than a breeder of many diverse species (which I am, so this isn't a self-serving plug), and either of those are 100X better than a flipper (someone who buys and resells many species, most of which they are typically only faintly familiar with, and specimens that they do not know the history of first hand).
OP, I'm glad your snake seems to be doing better. Adorable little guy.![]()