Backpack Expander

So just fooling around waiting for a timer to whittle down. I clicked on the third backpack’s final slot to see what it would take to unlock it. To my surprise it was 666 expanders…

These expanders are 5 diamonds or basically $.50 each. Does anyone really think the backpack slots are worth over $300 a section? This seems to be rather bizarre. You’d think one expander would unlock one slot. Obviously this is not the case. Is this actually intended?

starting in the second backpack the first extra slot costs 2 expanders, each additional slot costs 1 more then the previous slot. slots must be unlocked top to bottom, left to right.
the third backpack’s first slot costs 20 and each additional slot costs 2 more then the previous slot.
you do not need to unlock all of backpack 2 before unlocking backpack 3. so the cost of 666 expanders is for 18 new backpack slots ( all in pack 3) which is way more then anyone could want. I guess it’s an example of a true luxury for the rich to have just to say they spend $$$
also an example of a waste of game-code. I’d wager no-one ever buys any from pack 3. Myself i got 1 from pack 2 and rarely use it.