m3.medium is an AWS EC2 instance with 1 vCPU, 3.75 GiB memory (Intel Xeon E5-2670 v2 (Ivy Bridge/Sandy Bridge)). In US East (N. Virginia) it costs $0.067 per hour on demand ($48.91 per month) for Linux; a 1-year reserved instance with no upfront costs $0.048 per hour, 28% less. Spot capacity is about $0.0138 per hour. It is sold in 11 regions.
Prices by region
USD per hour, Linux. Reserved prices are no upfront, standard. Cheapest on-demand first.