would you even consider to throw these into normal trash. Here in Germany, that would get you fined - (almost) empty laser printer cartridges are nearly on the same level of nastiness as old engine oil.
On the other hand, if you do not find a commercial recycling program you like (every toner manufacturer and seller on the German market has to take back its empty cartridges at zero cost, and of course we also have companies which specialize in refills and pay a few dimes for used cartridges), every communal recycling center accepts toner cartridges free of charge. And in case they'd manage to make some bucks of them, it goes into the city budget. No need for charity shopping.