I’m a tight arse when it comes to packaging, I save any packaging I get from parcels and re use. If anyone complains I’m saving the environment
I have bought packaging stuff from B&M though which is reasonable. Parcel tape seems to last a while as well. For designer stuff, I would personally use DePop but Vinted has a tracking thing in place so unlikely for the buyer to say they never received. If they didn’t receive it Evri/InPost for example would say it’s lost and buyer gets refunded and you get your money as well (I’m not sure about Yodel I’ve not used that). Maybe try selling you other stuff first and see how you get on?