I suspect that rental gear as opposed to her very own is just not something that matters to her. As much as it is hard for those of us of one mind to fathom those that feel differently, these differences do exist. Just like some of us could not bear driving a 18 yr-old, very basic car and some of love the fact that the normal expected life of our car is gone but because it stiill runs fine and it's like we're driving all these extra years for free.
I know lots of people whose phones cost more than my car :blinking:
But each one of my 2 canister lamps costs more than their phone
She might enjoy her own gear but I'd be careful (a) about not being pushy and (b) about not doing things like this without her input - apparently she gave you a shot across the bow last time you did that! I think you should just keep the offer open but don't buy anything w/o her OK. Until then invest your cash on other things like some fun diving for both of you as well as books, equipment, classes ect WHEN SHE DECIDES she wants such things.
Remember: when mom's happy, everybody is happy. When mom's not happy ain't nobody happy.