The price varies by many variables such as wood species vs. painted, thickness of shelves, number of shelves, core of shelves (ply vs. particle board), mill work, additional features such as lighting and as well as the cost index of your geographical location.

Wow, I didn't even think about floating shelves, but they look great in the pictures you posted. I actually may like the floating look more than built-ins! Thank you so much- this is definitely a really good idea.

If you had a craftsman build them it can get expensive depending on if the wood is paintable or stainable. Floating shelves are great but can be expensive especially if they are long. I have seen a few sites where they took some off the shelf bookshelves, added trim and they appeared to look built in.
www.justagirlblog.com/billy-bookcases-diy/

Floating shelves is indeed a great look. Recognize that the sheet rock will need to be removed, brackets bolted to the wall studs and then new sheet rock. This is not complicated but it will create drywall dust in the house and the area will need to be repainted, it is good to be aware of this necessity in advance.

Thanks, I really appreciate that insight. Not quite as easy as it first sounds, but pretty outcome nonetheless. Thanks everyone!