Pricing for @vercel/sandbox is super competitive at $0.0106 hour at 1GB RAM and $0.0128 per core hour at 10% CPU utilization (with dev servers CPU utilization may be even lower). Notably, and in comparison to another similarly named product that magically shipped on the same day, it also has no other dependencies on Vercel infra. So, you can absolutely use it, when your app runs in your own infra or in another managed hosting provider.