meanwhile I found quite often some shop implementations on different websites offering merchandising products for the respective website.
Therefor there are shop provider where you can register (mostly for free), design your products, implement the shop-link into your website and get commission for the sold products.
Some of them are:
http://www.spreadshirt.net/
http://www.cafepress.com/
...
Now I'm asking all of you highly experienced people

Any experiences, other providers, ...?
Thanks and many greetings,
FELIX