Amanda Bynes -- I'm in a Purple Haze

Amanda Bynes took a page out of Wiz Khalifa's playbook Friday night in West Hollywood ... no, she wasn't rapping -- the troubled actress dyed her hair purple.

Amanda hit up Nine Zero One in West Hollywood ... we're told it was just a random salon walk-in. She stayed a few hours and we're told she was very polite.

Amanda paid with the little money she gets -- $50 to $100 a day.

As we previously reported ... Amanda's grousing she doesn't have enough money to get a hotel room for a night -- on Wednesday she roamed all night and fell asleep Thursday inside an L.A. mall.