my Subaru squeaks Once it hits 2500 rpm but it sounds like it's towards back of engine

Probably the pilot bearing for your trans input shaft.

What's that cost

Are you looking to do it yourself or have a shop do it?

Probably a shop

Then I can't really give you a reliable cost on that because every shop has a different cost per hour and some may bid the hours differently so find the shop that you would like to have do it and ask them. But I can tell ya looking into it a little more there's 2 things it could be, either the pilot bearing or the trans input bearing (which would be a more expensive repair) but without hearing it in person I can't tell you which it is for sure.