Going by what the first comment has said, you have different options, which is either to pay the high fee, create a channel on the Lightening Network, or wait for the transaction fee to drop. But I have a suggestion for you, and before then, there's a question you have to answer. Is the bitcoin in your wallet the only fund you have in your name right now? Don't you have some cash at hand?in your safe or in the bank? If you have some money on you, then you can as well convert some fiat into any cryptocurrency that the shop is accepting apart from Bitcoin. For example, if the online shop is accepting doge coins, convert some of your local currency to doge, then go ahead and buy your hat.