When using the toolbox command:
service plans are not copied/imported.
The request is to add the feature to both copy and import/export toolbox commands.
The workaround is to use the 3scale API Service Plan create endpoint, however it doesn't have all the settings to create the service plan as you'd do it from the admin portal UI: setup fee, trial period and cost per month are not available in the 3scale API, so it is not currently possible to automate the full process of copying-importing/exporting a product if it has service plans.