How can i stop getting bored of all my purchases.?

its as if im on autopilot- i buy it and get a huge buzz from having something special and new. then a few months or even a few weeks later im bored of it and sometimes regret even buying it. i bought a 50 dollar pair of steve madden sunglassses and dont even like them anymore. they dont suit me .. buying pressies for myself ca sometimes be an instant mood lifter- just like eating chocalate