The branded cut diamonds have their own websites with lists of distributors included. Usually, there is no note on prices - and these can vary between sellers. Hopefully there is one in your area that could show you some stones.
I can''t really help with the "where else" question as my square h&a is from GOG.
I do, however get to see it in person every day
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I love it! It is super sparkley and I love that in certain lighting I can see the arrows. I know there has been some mention that perhaps it''s not "square enough", however not one person has asked me if it is round. Everyone always says, "ooh, it''s so sparkley, I love that it''s square!" But they really don''t know what it is & I''ve had a couple of people ask me if it was a Princess cut (????).