With a reserved instance, RDS starts with $20/month for the small, $92/month for the large, and it's easy to change the size as the need arises. Heroku Postgres

With a reserved instance, RDS starts with $20/month for the small, $92/month for the large, and it's easy to change the size as the need arises. Heroku Postgres starts at $200/month, which is more than I'd want to pay for an early-stage project that I'm still experimenting with.