@Renard - If it was
too cheap, Onee-san would psychosomatically develop an allergy to it, half her body would turn green, and she'd suicide from knowing that her body rejected a sign of her beloved Minoru-kun's love.
If it wasn't cheap enough to create an allergy, she'd play with it so much that her finger would swell up, they'd have to cut it off, and she'd suicide from knowing she destroyed the ring given to her by her beloved Minoru-kun.
It...
might be too soon for a ring.