Seems like a pretty good deal nowadays for a complete bolt ($69). They also have some other pretty good deals, gas block for $5, charging handle for $8...
https://www.combatarmory.com/combat...-mil-spcc-bolt-carrier-group-made-in-the-usa/
https://www.combatarmory.com/combat...-mil-spcc-bolt-carrier-group-made-in-the-usa/