1. You are not talking rechambering, you are talking rebarreling. Big difference in cost.
A barrel blank will cost $300 +- and another $200 or so for chambering (or rehambering) to a 260.
is the place to go to look for prechambered savage barrels.
Shilen sells prefits for under $500 and Fred Moro at Sharp Shooter supply has them on hand also.
Seeing a how it is a budget build I would go the savage route and watch savageshooters forum for the bargains.
Also, might want t consider the 6.5x47. Much better brass, same ballistics and not finicky. the 260s are sometimes finicky. I have both and like the 6.5x47 much better.