There is very little growing out at wholesalers IME.
They get them in, they sell them, they go to LFS's. Most corals do not stay long at wholesalers IME.
JME
There are some retailers who do grow corals out, farm them, sell off the frags from parents but this is rare.
It just costs to much to operate like this. Mark up from the wholesalers is nothing compared to the markup from the LFS's IME. IME most LFS mark up about 300% or more, which sounds like a lot before you take in operating costs and losses. For example wholesalers can sell a TR seahorse for about $10, the consumer pays at least $30 and often into the $60 range.
Personally I can get things cheaper then my LFS but like to support the local industry myself, even on dry goods etc.
JMO