I think I read a retcon where it was stated that Tessa was actually working for Xavier during the DPS, and that Tessa regrets not helping Jean escape...
First that was 35,000 total. Assuming you want a basic Raise Dead, that's 5,000 GP worth of diamonds each casting. If you're worried about Superman's...
Not going to lie, a lot of the "appeals to authority" and attempted "this wouldn't work because it makes him feel old" arguments still end up quietly...