The 10 invites come from the BMAH. Their will be 10 invites sent out on the BMAH each day or something to that efffect. They haven't said how many individual player invites go out but yea it can't be 10 or any reasonable number. That would remove the exclusivity from it and apparently on the ptr it's only one.
There is no reward, so any profit you make from this is just the profit you would otherwise make from people being so insecure they need irrelevant achievements for their personality/ego.
There we can discuss how it's wise to get the money of millions of subscribers and spend in content that will be accessible to few thousand exploiters, instead of stuff that those millions ask, like new player models, fixed Stormwind, the pet journal they showed at the concept...
I know this isn't the case, but...
If someone buys a Brawler's Guild invite for 200K, then gets 10 invites to sell, then there's no logic that dictates he will sell those invites for 21000 gold a pop, only making 10000 gold profit in total.
What logic does dictate, obviously, is that he realizes these invites do sell for 200K a pop - hell, he just paid 200K for one -, and thus he'll try to sell all of his 10 invites for 200K a pop, making a sweet profit of 1.8 million.
So, even if this was the case; even if you did get 10 invites to give out once you get in, the whole "math behind" this situation is completely wrong.
we will be • when you will be no more
At the most they might let people invite two people at a time to the Brawlers Guild.
So if you need to buy your way in to the Brawlers, how is the first one going to get there?