What is a high end Acropora?
Prices are crazy when one is looking to purchase a named tenuis or other Acropora with a unique color morph. It is a bit funny (not in a mean spirited way mind you) to ask where to buy when the source was listed. Basically you are looking for a hobbyist who has a side hustle and undercutting the source of origin.
As mentioned, forum trade area, FB, ebay, are also possibilities. Just be aware that you may, or may not, be getting the real deal. If I was in your shoes I would be just looking around at Acropora tenuis frags and see what catches my eye and ignore the name unless it is something that you really, really, want. And then you would just pay the price.
Good luck on your journey.