db.x2g.8xlarge is an AWS RDS size. In US East (N. Virginia) it costs $5.216 per hour on demand ($3,807.68 per month) for PostgreSQL, Single-AZ; a 1-year reserved instance with no upfront costs $3.025 per hour, 42% less. It is sold in 5 regions.
Prices by region
USD per hour, PostgreSQL, Single-AZ. Reserved prices are no upfront, standard. Cheapest on-demand first.