Is there an upper limit to Ubuntu One Storage Subscriptions?

At Ubuntu One Services it is possible to purchase 20GB of additional storage space for $29.99/year. There is also a box which appears to work as a sort of quantity selector. My question is:
Is there an upper limit to the amount of 20GB subscriptions you can purchase at any one time?

Solution 1:

Yes, there is an upper limit. You cannot purchase more than 429.496.728 20-packs. In practice, this is the same as it being unlimited. If you do find that you need to purchase more storage than this, talk to us.

Solution 2:

Currently, there is no upper limit of how much you can purchase.