annemarieke...
try the silverprint.co.uk
i live in israel and i have less things than u in holland. my main sourse for the things (like silth, selenium etc that i cannot find here) is fotospeed. they make orders and send directly to me. for u it will be even cheaper because of the posting prices.
if there is something that fotospeed has not in their catalog or u prfare another brand than the silverprintco.uk