A friend had a .243 Winchester 100 rebored out to .358 that worked out great.
The result was a rifle the factory never made - a .358 Winchester 100 Auto. Unobtainium, well worth the cost - and no barrel available to buy, in that case.
I suppose, if you already had a replacement barrel for cheap $$$, it would cost less than a rebore - but you wouldn't necessarily have the original barrel markings, either.
Where most folks err, is in getting a little carried away, IMHO - like not only reboring, but also rechambering to (say) a belted magnum case, which leads to bolt face and feed rail work, etc, etc, forever and ever.
If the arm is rebored to a larger caliber, using the same basic case, it's very cost-effective, indeed.