I notice generically cloud infrastructure providers (like Digital Ocean, Linode..) offer "MongoDB Cluster" starting from 1GB of RAM at the cost of 15 usd.
The same providers offer "Virtual Personal Server" with 1 GB of RAM at less than 7usd.
Are there any valuable reasons (technical.. resources.. minimum requirements..) is advised to get the cluster when with less than half price is possible getting the same by a VPS?