History shows this will work.
It really is sad that petsmart is allowing this and as brigitte said should really be more concerned about it. The most I have seen for an adoption fee is 200-300 and that was if a random purebred cat somehow ended up in a rescue as a kitten. It's hard to say if the IRS would do anything about this, as it may be the digression of the charity to choose however much they want as an adoption fee, as long as they have a reason for it. In regards to the rare breed part, most people don't know the majority of cat breeds so if you told them a scottish fold was a rare breed they would nod their heads and move a long. While savannahs may not be rare these days, I've still never seen one in person, so it would stand that the average person that hasn't spent 7 months researching them would find them to be the most amazing thing they have ever seen. At least I would .
