"Kaufen": To acquire or invest in. This emphasised the mutual transaction of money from a commodity in unambiguous conditions (Alright, it can be used metaphorically likewise in an identical vogue to English: "Das kauf' ich Dir nicht ab" = "I do not buy [=believe that] that"). I also recommend the https://meineupdates.de/ein-einkaufsfuhrer-fur-massivholzbetten-worauf-sie-achten-und-wo-sie-einkaufen-sollten/