I created a VPC just by doing

new awsx.ec2.Vpc("name", {})

. It looks like it created a private subnet and a public subnet by default and the way it secured the private subnet is with a NAT Gateway. Why use a NAT Gateway instead of just using a Network ACL? Is there some advantage to NAT Gateway that makes it worth the extra cost?

NAT Gateways aren't just for security, they route traffic from the private subnet out to the public internet

Ah, got it. Cost isn't that much of a concern, but I just have an RDS instance in the private subnet right now, so it sounds like I don't need a NAT gateway or instance in that case