Check this out.
This is CSC's Canon 7D PL Mod. Not the Hot Rod, this one was precision made in Germany and it just feels awesome in your hand.
This kit rents for 300 a day, minus the Master Primes of course ;) That's so cheap and if you've already got a set of PL lenses for your A cam, you can get another angle for another 300 bucks. The only downside to this is that it's the 7D! You could probably get away with it for a 30 sec spot or some web vid but I wouldn't want to go there for anything even slightly substantial. They would love to be able to offer the 5D this way but the sensor is too big for most motion picture format lenses so vignetting is a real problem. Bummer.