About that money Luce didn't quite accept and didn't know how to use... she ends up effectively using it to buy the book he wanted. So it's almost like Elma used most of the money to buy something for himself, but with extra steps through Luce. Instead of paying 55m, he got it for just 39m, 9mil over the market price. Still overpriced, but not as bad.
Luce is too kind and perhaps naive, but I suppose one can't really put a price on feelings, and she's doing this out of gratitude for the incredible turn on her fortune after partying up with him.