Sigrid,
Have you tried this: http://www.parapublishing.com/

Dan Poynter is a self publishing guru - respected in his field - seems like a nice guy, too. I transcribed his presentation for the NAWW and he gave a lot of good advice about marketing books. A regular self publishing pioneer, that man. I'm no expert - just offering you another place to look in case you hadn't seen this.
I've also heard about having book signings in unusual places - 'think outside the box'. Good luck. Sometimes it seems like writing is the easy part and marketing is the hard part.