Breakfast topic: Pay for play

My realm forums recently had a good laugh at the expense of a recently transferred paladin who kindly offered to tank Black Morass runs for the low, low price of 125 gold (50g if you made the group!) But his business proposition made me think. I often see low-levels offering gold for run-throughs of unpopular instances like Gnomeregan, Uldaman and Blackfathom Depths. Is this really a common practice?

I've only been paid to run an instance once -- not too surprising, as my main's a rogue. My guild had stopped raiding a week or two before, and a slightly less-progressed guild was short on rogues for AQ40. Since I wouldn't be getting any loot, the guild offered to pay me some gold (I think about 20) for repairs and my time. I went, helped them kill a few bosses, and ended up accidentally embarassing the raid leader ("LOL you got out-DPSed by a girl. Get back in the kitchen!") Needless to say, that was the last time I ever got paid to run anything.

Have you ever been paid to run an instance or do a quest? Have you ever offered someone else money for their time?