When I logged in to my site this afternoon, I saw that the link to kaufDA.de was broken on both my original post AND on the button. I couldn't open kaufDA's website, either. Although I checked the button code and did some summary research BEfore placing it on this blog; I can't be certain that their website or code hasn't been altered since then by someone hacking into their website.
Hackers are malicious, and their ways are many and devious. Many websites and visitors are compromised by malicious code inserted into buttons or links. Until I see that the kaufDA.de website is stable and that no harm will come to my visitors by clicking the link and/or button or even visiting my page, I have (at least temporarily) taken both the post and the button out of the public and behind-the-scenes section of my blog.