I went with the Amberbebe one because of the explicit note about guaranteeing the work and the replacement/repair service, over the cheaper Ebay ones. Plus, I bought the mother baby set for $60, which the ebay ones didn't offer
I went for a dental x-ray the other day and didn'th ave to take mine off because it has no metal in it, which was a bonus, cos I nearly lost my earrings after having to take them off!