Where can I buy lots of cheap stock photo slides, negatives, and transparencies

[tearcut1]

Where can I buy lots of stock slides mainly, negatives, transparencies and photo books that are royalty free for copying or pic taking.

Looking for a mixed bunch of themes.

Interested in old school manual darkroom photo - manipulation for graphic design purposes.

[domaz]

Estate sales. Lots of slides and occasionally older Large Format negatives show up at those.