I cannot speak to pricing. No idea.
I strongly caution against trying to create any cross-vendor grade equivalence, it will fail. Most vendors grade their own product on a sliding scale that adjusts for size and overall quality of a given batch - Mikimoto does not.
My recommendation is in post #27.
I beg your pardon for misunderstanding you. I am merely trying to synthesize all this information and come to a conclusion on what to purchase. Thanks very much for your time and feedback.