Is my 1925 2 and a half dollar Indian head gold coin extra rare because its upside down. what is the value?

It is my understanding that they were hand stamped without great care of location of design on underside. In any case the one I have is not quite upside down but very close.

Correction

US Coins were never hand-stamped. If you look at the front right-side up and the reverse is right-side up when you turn the coin from top to bottom, this is the normal orientation for US coins.