> In getting my mother-in-law's home ready for sale as she has moved into an
> assisted living complex I found a 20 volume set of "The Writings of Thomas
> Jefferson" published in 1903-4. It is the 622 copy of a 1000 limited
> publication and is in good shape. I need to find out the worth of these
> books and how best to market them. Could you be of any help? 

What you have is referred to as the "Memorial Edition" of Jefferson's
Writings.  Exactly what its value is becomes an interesting question.  I
will tell you of recent events that I am aware of.  I understand a set was
offered within the last couple of months on Ebay.com at a set price of
$5,000 (yes!), but that the bidding was in the $500 to $600 range.  This
edition, or one similar to it, has just recently been put on the Internet,
is available free, and that fact would probably tend to reduce what a person
could get for the printed edition.  Some copies of the printed edition are
beginning to disintegrate.  The online edition is available at the following 
URL:

 http://www.constitution.org/tj/jeff.htm

There is something confused about that online edition: the editor is listed
as Bergh, instead of Lipscomb and Bergh.  There are only 19 volumes up (the
last of the 20 vol. set is an index vol., and may have been thought
unnecessary to go online).  I have a set of the books you have in xeroxed
form.  I have not had time to go through the online edition and figure out
why there are these discrepancies.  But that is not particularly relevant to 
your inquiry.

Finally, just last week, a friend told me he saw this 20 vol. edition
available here in New Orleans at a used book fair for $60.  I advised him to
grab it, because he could probably sell it for much more than that on Ebay.
I am not sure what the outcome was.

My advice would be to offer it for auction sale on Ebay.com.  That is almost
certainly the best way for you to get the best price possible for it.  I
understand that many used book retailers have abandoned their shops and
conduct business exclusively on Ebay.  I would suggest that you might make a
minimum bid of $300 and then see what happens.