a1.metal is an AWS EC2 instance with 16 vCPUs, 32 GiB memory (AWS Graviton Processor). In US East (N. Virginia) it costs $0.408 per hour on demand ($297.84 per month) for Linux; a 1-year reserved instance with no upfront costs $0.257 per hour, 37% less. Spot capacity is about $0.3818 per hour. It is sold in 9 regions; the cheapest is Asia Pacific (Mumbai) at $0.408 per hour.
Prices by region
USD per hour, Linux. Reserved prices are no upfront, standard. Cheapest on-demand first.