I personally search for things on all these: Ricardo, Tutti, eBay, Amazon.
It’s kind of a pain, but the price difference can be significant. Sometimes Amazon (new) is cheaper after all the shipping fees etc.
I do that for smaller items like PS4 games (where I don’t care if the item is new or used, it’s the same game).
For selling, I’ll try on Tutti for a few weeks first (because it’s free), and if it doesn’t sell there I’ll list it on Ricardo starting at 1.- because it will almost always end up selling there.
What about others here? What’s your secret sauce for buying second hand items in CH, and what do you buy? Or do you prefer to buy new anyway?