>Does precision strike cost more than circle?

Nope.

>I had already learned circle and now (getting points back) I
>cannot practice precision strike (or any other skills in the
>other paths).

This has happened to a handful of thieves. The points were adjusted a little while back, and the skills you have already total more than the maximum amount of points you were alotted. Alas you are left without precision strike (but still more skills than a new thief who rolled up today).