painting is always easier than rebuilding.
That said, a beautiful bookcase makes books (I LUV BOOKS) look even better.
If you remake the bookcase using good materials (why bother replacing of you're going to go cheap), you're looking at the upper end of your range.
I much prefer my bookcases (and any cabinetry) with a kickplate. You'll find the same on almost any kitchen cabinet and most similar furniture ... so ... do the floor first, easier than trying to get it installed right under the kickplate.
The main reason I like kickplates for bookshelves - did I mention I LUV BOOKS? - is that it keeps the books off the floor where water damage is more likely to happen.

pete