In December, Gaiman announced that this will be his last book signing tour.
Subterranean Press, also sent out an email this week stating that they still have a few copies left of the Wm Morrow signed, limited edition (priced at $150). This edition has a different cover and illustrations. Usually these are limited to 1,000-ish copies, although no numbers are mentioned on the Sub Press page. Copies can be got at a slight discount elsewhere, with a little Internet sleuthing.
To keep tabs on where Gaiman will be next, check out the Where's Neil? section of his Website.