db.m8gd.large is an AWS RDS size with 2 vCPUs, 8 GiB memory. In US East (N. Virginia) it costs $0.1976 per hour on demand ($144.25 per month) for PostgreSQL, Single-AZ; a 1-year Database Savings Plan costs $0.1581 per hour, 20% less. It is sold in 12 regions.
Prices by region
USD per hour, PostgreSQL, Single-AZ. Reserved prices are no upfront, standard. Cheapest on-demand first.