I think the $10 package should suffice to run openerp

Hello, there

Choosing the right Droplet plan depends on your workload. An oversized Droplet would underuse its resources and cost more, but an undersized Droplet running at full CPU or memory would suffer from degraded performance or errors.

In your case, you can start with a smaller droplet and then upgrade in the future if this is needed. I’ll recommend having at least 2GB of RAM.

You can also resize a Droplet to a larger plan after creation, including resizing to a larger Droplet plan of a different kind. For example, you can resize from a Basic Droplet plan to a larger CPU-Optimized Droplet plan. See the Droplet pricing page for a full list of plans and prices.

You can always check our tutorial on Choosing the Right Droplet Plan

https://docs.digitalocean.com/products/droplets/resources/choose-plan/

Hope that this helps!
Regards,
Alex