Hi Stefan,
Reichelt is a place to check *often* because they are developing their stock "on demand" i think. The "MIDIbox" forum people searched for the PIC18F452 and the MAX525 that often, that Reichelt has them in stock now! (We had to buy them in the netherlands at voti.nl / MAXIM directly or in vast amounts or get them as samples before...)
A good place outside germany is obviously profusionplc - specialized in audiotransistors/IC - they sell small amounts / single parts online at fair prices.
Last option (as ever) is farnell - prices are sometime *not that fair* (in good ol' german: "Apothekerpreise")...but better than searching forever...
hope it helps you and good luck!