Why do we like sales?

At this time of year, it's easy to be seduced by sales tickets, promising an item at a price advertised as significantly lower than at a previous time.  In the UK these sales have a code of practice which is supposed to protect consumers from the ploys of companies touting a discount where non actually exists. But we're still seduced by the purported value of the saving.. of getting something for less... and many stores get around the rules by advertising higher prices in remote stores for 28 days previously..

You would have spent £100, now you only have to spend £50... the ticket exclaims, but we somehow fail to acknowledge that the item still costs us £50 (and before the sale, probably would have cost us £50 if we'd have been considering the item for some time..)  A shop is rarely going to offer for sale an item cheaper than they bought it, and below the price they can afford to sell it.   A sale price then is often not only a lie, but in the promise of a 'saving' you in fact don't make, it's an additional deceptive sham.

• I wonder what it is that attracts us to such things?  
• Why are we so easily mislead?
• Do we value something more if it costs us less? 
• How much are our feelings involved in our decision making?
• What does it say about what we need v what we want?
• How much does 'impulsiveness' play in our shopping habits? - and what does that prove about the fruit of 'self - control?'