Restrict subscriptions by country

I want to use Membership Pro to manage memberships that include a magazine. The problem is that the cost of posting varies greatly from one country to another. Besides Membership Pro, I have a base price for my membership in Canada, one for the USA and one for all the other countries.

Right now, I have no opportunity to do that in Membership Pro. I have to create a plan for each region (Canada, USA, other countries) but there is no way to prevent a member from Belgium to select the Canadian member plan.

I see thus two possibilities:

1. To restrict subscriptions to a specific plan by selecting one or several countries.

2. To be able to vary the price depending on the country, either directly from the plan, or by making the "Country" field having an impact on the price of the plan, like the other custom fields.

Thanks!