Do you want a new bolt or a new bolt carrier group?
Besides all the ado about staking (which you can do yourself with minimal expense and 20 seconds) and the various opinions (mostly without anything to genuinely support them other than "more is better", specious logic at best) about what constitutes "proper" staking and the tangible difference between a semi-auto and M16 carrier (both are legal in your semi-auto) a bolt carrier is pretty much a bolt carrier. Make sure that the carrier key is installed correctly (staking is more a fail-safe to cover an improper install) and a carrier is a carrier.
The bolt is a different story. It is the part that takes all the stress, does all the work and is prone to failure. Even the highest quality bolts fail eventually and there is no guarantee that a more expensive bolt with all the QC steps done will outlast a batch tested bolt though the likelihood of getting a bad bolt straight away is essentially nil on the fully tested bolt. The bolt and the firing pin are the two things that I would keep a spare around for. I wouldn't bother replacing the bolt until it fails, though.
If the rifle is working fine, I wouldn't swap an M16 carrier in "just because", either. Spend the money on ammo. Practice can make you a better shooter. A new shiny (or better, dull) bolt or bolt carrier won't make the slightest difference in that regard.