The condition of needing to buy, as a silent emotional definition of one's purpose: conquering whichever store one's in by acquiring it's most desirable things.
Part of this also involves the emotional territory of having something, so someone else will *not* get it. It's actually use or utility or superiority to other objects is actually a side issue - a rationale rather than a reason.
There is within this also a touch of the gambler's high; the expression of the deathwish, the brush with chaos, the hanging-toes-over-the-edge-of-Hell feeling of spending one's wad on something cool.
Anyway, that new Mac touchscreen sure looks sweet.
Steve Martin - "That's all I need!"