A little from me (as Boonex staff):
* we don`t get any comissions
* I pay too (as my own home account 'Aramis') $20 (as Boonex staff)
but one, I pay once, so in this month I become expert here, so no need pay more, yes, my status of contributor is off now, but expert status will worked all time
this is just for service.
It give us one good advantage, we save us from false expertzzz, cheaters etc like CodyT, remember? he always register new account and sell and sell stoled mods
second - admin see more approving of mods, it second protection from selling bad, incomplete, not-working mods. We (I hope) don`t steal ideas and code, we (sure 100% about me) don`t need your mods,
For example I never buy any mod before, just because I don`t need it, all mods and all work I can develop myself.
All admins must just check and approve mods if it meet all requirements

So yes, pay just once 20, and be faster - publish your free extension and become expert, welcome!

Regards