Yes, it's possible.
You can do this by using an additional plugin: http://www.vnecoms.com/magento-marketplace/plugins/vendor-membership.html
With the Vendor Membership plugin, marketplace owner can create multiple membership packages. each package will relate to a vendor group. (Platinum, Gold, Bronze...). You can set the price and duration for each package.
After vendor purchase the package this account will be upgraded to corresponding vendor group.