Given values seem somewhat... off.
Unlocking Storage row 6 costs same as Backpack Row 7, 145/725. Storage row 7 costs 195/980.
I distinctly remember the Storage started with less than 4 slots, but my memory is never quite reliable; I shall check once my second char makes it out of Delton. The Backpack clearly starts with 4 slots, however; the article is contradicting itself. I'll see about editing it once I have some more data.