JustUnfollow Premium was launched on the 5th of August. It's been well received and users are finding the price to be good enough to go for the Premium service.

With JustUnfollow Premium you can unfollow and follow as many users as you want per day (of course, the normal limits that twitter has set will still apply). Premium users can link as many accounts as they want. 

To upgrade your account to Premium, login to http://justunfollow.com and click the green 'Upgrade' link at top right corner.

You can make payments either using your paypal account or any credit card. Hope you like what JustUnfollow Premium has to offer.