Sarah hadn't been to Diagon Alley in a while. She had been to its counterparts in the Muggle World and its fellow wizarding equivalent in every continent, but she likes Diagon Alley best. It was.. hers. Of course not legally hers, but it was familiar to her.
Before she could get shopping though, she first had to convert some of her muggle money to its wizarding equivalent.
She walked up to the counter.. she loved the polished wood. If the goblin wasn't so close she would have smoothed her fingers across it.
"Hi" she said with a smile. Hello was a word invented 200 years before in order for people on the other end of the muggle telephone to know that you were there.
"I would like to exchange my 150 pounds for wizarding currency" Sarah said confidently. She was 21 years old now, and the money was part of an advance she got on her muggle novel.

She held out her money. That was a lot of money. Out of the corner of her eye and looked to make sure that there was no one to snatch it from her. Just in case,, she put her hand on her wand in her holster.