This Clear Crystal Flower Ring by Chanel may be rented from Avelle.com for $43 per week. I don't know the exact retail price of the ring but it's Chanel so you know it's up there.
While Chanel-inspired rings can be found just about everywhere, this particular crystal flower ring currently available at Forever 21 seems to be an especially charming homage. For $6.80, how can you resist?