To answer your last question first, it's MORE expensive to have something custom made because of the time involved in design and one-off production.

As for how to find people who do this sort of work, search for 'furniture makers', 'cabinet makers' and 'custom furniture' in your area. Depending on where you are, there may be lots of them or none nearby.

As far as design vs. building, it depends on what you want made. If you need a simple shelving unit to fit in a wall alcove, that's pretty simple and any cabinet shop should be able to design and build. If you're looking for a high end unique piece of furniture like a table made with a huge tree slab, it's more complicated to get that right and to build it than it is to make shelving, so you need a different type of shop, probably.

If you have any shops or galleries around that have such pieces displayed, you might be able to find local craftsmen that way.

Thank you so much for providing me with such information, I really appreciate it!

Try the term "bespoke furniture"?

Casey