Basically the title. Looked everywhere and cant find where to buy them at. Mine got stripped and I had to cut them out and need replacement.

 

Any local muffler shop. Alternately you can just use some grade 5 or 8 bolt/nut with flat washers, use high temp anti-seize on all your exhaust bolts for easy removal in the future.

Permatex 80078 is great for pretty much all fasteners on vehicles that need anti-seize and corrosion protection on threads.