The reason I say joiner, bednobs, is we had a similar handrail to the one you want, put up in our previous house when we had an extension built for a grandparent who came to live with us. The handrail was the last thing the joiner employed by the builder did.
We've recently had our bannister spindles replaced, and that was also done by a joiner.
I suppose it depends on how 'handy' a handyman is though..