AMD High Performance 1 vCPU, 1024 MB RAM, 25 GB NVMe, 2.00 TB Transfer
Emails are sent using zoho mail free tier. If absolutely necessary an additional $2 for two users (admin and noreply) /month would be added.
Total cost (yearly): $96 + (some tax).
As things stand right now ~$100/year is easily affordable but as the number of users grow, it largely boils down to egress and storage costs. I can personally bear most of it, but if it starts booming then I'll have to rethink about options.
Just FYI the best deal for a vps I could find was a VPS S at contabo.com
For 5.99€ you get a 4vCPU, 8GB RAM machine with 32TB egress traffic, unlimited ingress included.
And if I understand it correctly, after 32TB you might just get throttled (I never scratched more than a few hundred MB). Ran a server there for 8 years, never had issues.
The management interface is a little old-school...
If you'd have to increase your vultr instance type, maybe a migration is also an option.
Their pricing and reputation is certainly good. However, it seems like they don't have simple full server snapshot support. I think that's mandatory at this point in case of potentially irrecoverable failures.