Seller doesn't play by the rules:
I won a no reserve price poster for cheap, but seller decided to cancel under the guise of some nonsense about quality. I'm pretty sure it was bc of the low price.

This is auction not donation,the shipping cost me more than your offer....be serious and adult

After winning and paying the auction, seller refused to send the item, demanding more money. Catawiki had to cancel the order. 

Condition significantly worse then visible on photos. Highly problematic communication with seller. Only thanks to the intervention of Catawiki support matter was resolved.

Never deal with this buyer
Indeed, after I canceled a first poster sale with this buyer, the buyer bids for and wins a second poster sale
I send him the set of posters that he won the second time. So he gets the batch of posters and says that 3 are missing (while I check several times before sending a package)
He also says that the condition of the posters is not terrible while in the photos and the description I specify the poor condition of the posters... he wanted me to lower the price otherwise he canceled the sale and that I had to pay the shipping costs for the return (imagine if you live in the USA, China, Australia, etc...)
I think he wanted this revenge for the first sale I canceled and took the opportunity to blackmail me
He's a dishonest person
In conclusion flee and do not make any business with him

Seller decided to cancel order after payment was done.