Those performing regularly country-specific or subject-related ebay
searches might be interested to try the search generator at

http://www.volny.cz/phist/stamps.htm

You can search by country of interest, by selected subjects (censored
mail, field post, perfins, postage due, prisoners´ mail, railway mail,
reply coupons, rural mail, ship mail) or by both and to narrow the
search by additional keywords. Fast and easy tool for advanced search
in the stamps category. Description or title search. Search is
performed internationally over all ebay sites.

Regards

R