r3.large is an AWS EC2 instance with 2 vCPUs, 15.25 GiB memory (Intel Xeon E5-2670 v2 (Ivy Bridge)). In US East (N. Virginia) it costs $0.166 per hour on demand ($121.18 per month) for Linux; a 1-year reserved instance with no upfront costs $0.105 per hour, 37% less. Spot capacity is about $0.0428 per hour. It is sold in 13 regions.
Prices by region
USD per hour, Linux. Reserved prices are no upfront, standard. Cheapest on-demand first.