I'm not sure how creating another premium account is the cheapest way to get another 512 more of tier. According to land pricing, it costs an extra $5/month to add 512 to your existing account.
According to the membership page new accounts cost "as low as" $6/ month so that's $12/year more expensive.
Unless you were thinking of creating 3 accounts to create a group and get an extra 10% of land for a group, I can't see how it could be any better at all.