are there any websites that sell Just the dust jackets for modern 1st edition books?

Hi.

Due to fact that dust wrappers for books were originally intended to
be disposable, and because they're intended to protect the book from
damage by taking it upon themselves, the corresponding books will
naturally outnumber original wrappers, so demand for wrappers is
likely to be greater than the supply.

It looks like these two sites are probably your best bets:

http://www.oddvolumesunited.com/cgi-bin/ovushort.cgi?djacketsSale

This site specifically lets you view dust jackets for sale. 

http://oddvolumes.com/cgi-bin/search.pl?=bits&sw=S&dbbr_title=all_entries&br_author=

This is a search on "odd parts of books," so you'll need to either
scroll down and parse for dustjackets, or use a search term to get
targeted results. Note here that the part field appears to be
freeform, so these are variously called "dust wrappers," "dust
jackets," etc. You could also just search on your book titles, of
course.

Note that you can register at both of the above sites to post a list
of your wanted items as well.

If these sites don't turn up what you're looking for, there are a few
smaller collections available as well.

Here's a guy in New Mexico, US, who has a list of available dust
covers:

http://www.delapena.com/Dust_Jackets.html

Another source, by publisher, is online at:

http://www.grantbooks.com/dust_jackets_for_sale.html

And it appears that some smaller presses offer replacement dust
jackets for their books, but there are too many to mention here. To
see if an individual publisher offers this, you could either check
their main website or search on "dust jacket" and the publisher's
name.

Finally, here's a little discussion of dust jackets that, while it
doesn't answer your question, might be of interest. Or not:

http://www.pbs.org/wgbh/pages/roadshow/speak/dustjacket.html

The search terms I used were, "dust jacket," "dustjacket," "dust
wrapper," and "dustwrapper."

Good luck, and if you find a blue and white dustjacket for an early
edition of Tess of the D'Urbervilles, it's probably the one that an
old roommate of mine threw away while I was out so the bookshelves
would look 'classier.'

I'm STILL mad about that.

Lisa.

Could you please clarify?  Do you mean, for instance, the dustcover to
the first edition of For Whom the Bell Tolls, or just dustcovers in
general that you can use to protect a first edition book?  Thanks. 
Elizabeth

i mean dustjackets for specific books, as in your Hemingway example. 
many people buy ex-library books at library book sales just for the
dustjackets, hoping to marry the jacket to a copy of the book that
they find without a jacket. i have many such books and want to find a
source for the jackets.