Dear Mr. public enemy,
Someone is going to have to clean the oil off of the fouled transmission and then re-examine it after a hundred miles or so. There are many places for oil to leak from a transmission: pan gasket, pan seal plug, cooler lines, B2 piston cover, etc. If anyone tells you where the leak is coming from over the web, they are either psychic or just plain guessing.
The cost of repair will depend on what exactly is leaking. If it's the pan and you need a transmission service anyway, the leak is fixed for free when they replace the pan gasket. If it's something harder to get to, you may have to live with the leak or pull the transmission out.
Good luck. HTH.