Did you know you could pay your transaction fees in Sestertius ??
Sponsored transaction fees in sestertius : Since this morning, it is possible for you to pay waves transaction fees in sestertius since waves sponsored transaction fees have been activated for this asset. Use it at your convenience for any transaction on waves DEX or for transfers with waves or any assets.

In the case you experience a Sestertius shortage, you can buy some on waves DEX exchange, trading them for Waves:
https://client.wavesplatform.com/dex?assetId2=BvQbMQ2g52dZpZUcu2syaedqFajUFhTpb5wHc35DprZN&assetId1=WAVES
trading them for BTC :
https://client.wavesplatform.com/dex?assetId2=BvQbMQ2g52dZpZUcu2syaedqFajUFhTpb5wHc35DprZN&assetId1=8LQW8f7P5d5PZM7GtZEBgaqRPGSzS3DfPuiXrURJ4AJS
or trading them for ETH
https://client.wavesplatform.com/dex?assetId2=BvQbMQ2g52dZpZUcu2syaedqFajUFhTpb5wHc35DprZN&assetId1=474jTeYx2r2Va35794tCScAXWJG9hU2HcgxzMowaZUnu