Man, this is still going. . .

OP: Sell your runs. It's not against any rules, though it may be seen as distasteful by some. Others won't care and will pay you, but largely, most players will simply ask their friends, or make new ones in pursuit of leveling together. Many players might even work out an exchange system (i.e. I'll tank New Dungeon X for you if you tank Y Instance for me. Cross Server PF is going to help out with this as well. PotD, if still relevant will be the "quick" option if queues are bad, and there's MSQ, leves, FATEs, random side quests, etc.

All in all, I won't say it won't be a lucrative market, but I strongly doubt it'll be a busy one.