"Kaufen": To acquire or obtain. This emphasised the mutual transaction of cash versus a commodity in unambiguous phrases (Alright, it can be used metaphorically also in a similar fashion to English: "Das kauf' ich Dir nicht ab" = "I do not buy [=believe] that"). Make sure you also look out https://meineupdates.de/ein-einkaufsfuhrer-fur-massivholzbetten-worauf-sie-achten-und-wo-sie-einkaufen-sollten/