The underlying requirement for a PayPal Business account, is that you prove you are a legitimate (in their eyes) business (according to their standards):
https://www.paypal.com/webapps/mpp/confirm-your-business
For a Premier account, the underlying requirement is that you prove your personal identity.
Upgrading from a Personal account to either Premier or Business is free.
https://www.paypal.com/us/cgi-bin/webscr?cmd=_run-signup-upgrade-link