While I agree with you, in this particular case, I think we can safely assume that the op is referring to the black milksnake L.t. gaigeae.
I do not know of any breeders, however I do see them come up on fauna and kingsnake pretty frequently. $230.00 seems a bit excessive unless it is for an adult. Standard pricing seems to be 100.00-175.00. In the fall of 2011 I paid 125.00 for a hatchling male that was priced 150.00 at an expo.
Good luck, they're one of my favorite milks.