For big market players like you, we strongly recommend to go with a good scalable cloud computing set up like AWS. To scale up; as a regular practice we suggest one or more than one EC2 instances behind a load balancer to accommodate the load i.e. the no. of products Vs traffic to your domain. At the same time, It also depends on your deployment procedures. If required, you may create an AMI from one instance and set up an autoscaling group to scale it horizontally.
However, for startups not expecting huge traffic and data very soon, a t2.small ec2 instance with 2GB RAM (or even t2.micro in free tier) can meet the purpose initially.