Microeconomic theory maintains that purchases are driven by a combination of consumer preference and price.

Neuroimaging evidence shows that distinct circuits anticipate gain and loss, product preference activated the nucleus accumbens (NAcc), while excessive prices activated the insula and deactivated the mesial prefrontal cortex (MPFC) prior to the purchase decision.

Activity from each of these regions independently predicted peoples purchases above and beyond self-reports they made. 

On a random tangent - but fascinating stuff, all this going on while we are completely unaware in that shoe store. What isn’t clear though - yes, the exorbitant price of the boots activates the insula in your brain, but where is the circuit that kicks in with some inhibitory neurotransmitter that makes you put the Eftpos card back in your wallet!! Â