I could see that. Cages can get bent. Mtb jockey pulley cages are both more abused, and are generally longer, which makes them more easily bent and more exposed. I can't think of many I've fixed though. The few I've encountered that had been crashed were far beyond bending back into shape, particularly because Shimano likes to use bushings on the jockey pulleys (and the upper one has to float too), so they bind up at even the slightest deflection. More gentle bends come from kids who drop their bikes.
While I don't use my BT3, I'm really not looking to sell it. Sorry.
The $100 or so I see them on eBay for now is just plain nuts, but the completed items history implies that you could get one to your door for around $20 if you have patience. It still seems nuts to me, as it's not a very useful tool, and an adjustable wrench or even a Pliers Wrench could do as good a job. IIRC, mine came with a Park pedal wrench (which IS a useful tool) at a garage sale.
edit: FWIW, my most used Park tool is their BBQ-1:
https://www.parktool.com/product/barbeque-spatula-bbq-1
It's a really nice spatula!