This specific tournament require an entry fee of 1.5 SPS for Novice/Bronze.
15 SPS entry fee for everyone else.
Each tournament has its own specific entry costs. From what I can see some still require DEC. Some require staked SPS + Entry fee. You would need to visit the lobby of an individual tournament to read its requirements.
RE: Splinterlands Tournament Spotlight: UNTAMED KOBOLD MINING EXPEDITION