Transaction costs are very volatile and often, you don’t need to set a high fee or you can just wait a few hours to send it. Many sites are not very accurate, but here’s one that could be extremely useful to check before you sent a transaction:
It will show the state of Bitcoin’s Mempool (all transactions waiting for confirmation and their fees in Satoshi / byte).
Just move your mouse over the last graph and see how much Satoshi / byte you have to pay that your tx will be included into one of the next blocks.
When you are using a good wallet like Electrum you can change fees. Exchanges won’t allow changing fees ofcourse.