Last I checked, IBM i pricing was heavily discounted on the 4-core servers which also did not provide for DASD expansion outside the box. Fewer cores and DASD expansion options allowed a discount on IBM i.
Depending on what you may want to offer in the cloud, user based licensing may also apply. Would any of the users need to authenticate against IBM i user profiles, validation lists, LDAP directory entries? Would users need Navigator or Access? User based licensing may apply.
A caveat - I have not kept up date on pricing lately. I confer with a business partner before getting serious about pricing.