I haven't hosted/run a site like this before. So I'm curious whether 17K a year to run a product like this is normal. If the author is willing to divulge the details, would love to know what takes the major chunk of that 17K.
Also in my costs are email (transactional via Mailgun, marketing via MailJet), DMARCian, AWS S3 for avatars and attachments, SSL (still paying for a wildcard, perhaps let's encrypt next time round), Google Apps for email to run the business.
It's realistic to spend around USD 10k per year running a moderately successful medium sized web business.
Found this list: http://www.s3-client.com/s3-storage-providers.html
S3 is all about controlling transfer costs, so I placed an Nginx file cache in front of my attachments and avatars and it obliterated my transfer costs.