+1 @curiousjim
How do we arrive at 90%? I love the sound of Gryphon Commander+Apex, but how do we reduce it to an equivalent 90%? Turntables, how high to climb aka spend to reach the 90%? Cartridges- how to get 90% of a sound like a Koetsu?
I understand the OP wants to come up with some number to maybe be a guide, but our different subjective preferences, commitment to this hobby, and very different budgets prevents a cost to be universally fitting.