The Fastmail pricing tiers are $3, $5, and $9 per month which is $36, $60, and $108 per year respectively. If you look at their primary competition their prices are on par or slightly better. Here is a sampling...
Google G Suite: $5, $10, and $25 per month per user.
Microsoft: $4, $8, or $12.50 per month per user.
ZOHO: $3, $7 per month per user billed yearly.
[0] https://gsuite.google.com/pricing.html
[1] https://products.office.com/en-us/exchange/compare-microsoft...