And speaking as someone with -9.5 prescription (ditto the wife), you've practically got eagle-eyes. ;)
What index did you end up getting, if I might ask?
Okay, just placed my first order (wife had ordered from them a few times).
I got the best one that didn't cost more money - 1.57 Mid-Index Single Vision. Did have to pay the $9 extra strength charge. Total with shipping was $20.90
They emailed after I placed the order warning me they'd be thick and asking if I wanted a different frame (or could pay more to make them thin). I said just ship em. Was pleasantly surprised, don't think they're that bad.
And the prescription is night and day from my old glasses that were a few prescriptions out of date.