I see people advertising single stamps in delcampe and they are only worth a few cents. How can the seller make any profit this way?
not all the sellers on delcampe are in it for a profit. many of them are collectors who are just trying to recover some of their costs and liquidate their extras, in order to make more purchases. also, some depend on volume to make a profit.
I see people selling via wensy.com and from what I could see, wensy doesn't make a profit out of any of it - where's the catch.
until they get themselves established as a viable alternative to eBay, and build a base of sellers with quality material at fair prices, they are offering free services. eventually, as they grow in volume and reputation, they will likely start charging fees.