[pepesza]

You can do Proof of Authority instead of Proof of Work to cut down costs.

The real reason behind techniques such as PoW instead of just Distributed Byzantine Fault Tolerance algorithms is scaling in terms of number of validators. Most of DBFTs (afaik Algorand is the only exception) don't really scale. Proof of Authority behaves similarly to PoW, since it also does not have that problem.

Go with DBFT unless you want to have huge number of validators.