Can I be banned for purchasing outside of cardmarket?

Hello people,

basically cardmarket decides how much I should pay on my shipment and sometimes for a single relatively expensive card the shipping price is ridicolously high.

Therefore I made some deals with vendors where I contacted them on cardmarket and bought outside the system.

I was wondering if this can lead to an account ban (basically concluding the deal outside of mkm).

I read the terms and conditions and nothing mentions that this is forbidden.

Thanks a lot!