Rihanna rocks her bargain buy. Photo: Dave M. Benett, Getty Images

Stars like Rihanna have their pick from top designers' clothes to wear to events.

From couture gowns to the latest accessories, we're used to seeing stars wearing fabulous things we could never, ever afford.

So who would have guessed that Rihanna would show up to a party in London this week in an $85 dress!

Yes, you read that correctly.

Rihanna wore this black cage-sleeved dress by Funktional, a new line by L.A.-based designer Jennifer Park.

The best part? Her dress retails for just $85!

Rihanna paired the mini with black tights and slouchy booties, but this look would be equally sexy with black patent heels or tall boots.

Just in time for your holiday parties, check out Rihanna's exact dress here, or browse more little black dresses under $100: