A bracelet

 "Excuse me, Miss!"
She gave him a quick look."I´ve already got a boyfriend", with a voice that just wanted him to go away.
"Oh, sorry. It´s not that. I noticed your bracelet. My girlfriend lost hers that was identical to yours. Can I buy it from you? I can give you two houndred for it".

"Two houndred for this? Deal!", she said and handed it over to him. He was beyond content with the deal

"A bracelet. A spellbook. And voilá! A magical bracelet that let you take on the appearance of the person that wore it the last time before the imbuement of magic into it."

"Now I can transform myself into this hot babe anytime I want"