Complete LEGO service packages, some old sets: De Klerk Speelgoed J.P. Heyestraat 164 (close to Vondelpark) Amsterdam, The Netherlands tel. 020-683 2017Speelgoedwinkel Otten Nieuwstraat 's-Hertogenbosch
Very old sets, unopened boxes from 60s and 70s; original trains; books: A toystore on the central square of Prüm, Germany (I have the address somewhere, watch this space.) Unfortunately, the owner is extremely cranky and impatient. Please bother him a little more from me.
Many old sets from the 70s and 80s and many separate components. Spielbude Hohle Strasse 4 58091 Hagen Germany
On the internet, check out: The Construction Site and this perpetual auction.
Koelewijn's auction with some really old sets in mint condition.