Commercial plugins are allowed to be-listed here. We are in no way involved with any payments.
Basically anything urlkiller like that is up to a plugin developer.
However this topic does bring to mind for me to add a "commercial" field for plugins/modules/skins repository system. (Not gonna detail it out, but there will be some overhauls on cotonti.com aswell with Siena 0.9.0)
On another note, I would have my commercial plugins listed here yet, but I haven't got my site fully setup yet
( which is really only 1 commercial plugin atm, as I don't count ones i've made specifically for Clients)