Experience
It's important to know who you're doing business with..
On samenkopen.net customers graded us 9,5 out of 10!
On ebay we have 100% positieve feedback!
Because Ebay ask high fees and is a terrible and slow system, the products and shipping on penuries.com are cheaper than on ebay.
If you google on "penuries.com" you can find many experiences of customers.