I have a link in the sticky post at the top of this section.
Anything can be expensive, but it doesn't need to be. The coarse stones don't need to be used more than once on a razor (unless you chip the edge), so the most cost efficient way is to have your razors honed by somebody with the hones and the skill and then maintain the edge with a finishing hone only.
Of course almost everybody I've seen on this site think they will be better off honing their razors themselves. Nothing wrong with this, but it's our choices what makes it expensive.