MTV News' Christina Garibaldi hit the streets of NYC to find out, visiting some of the Big Apple's most exclusive big-name retailers to find the pop prince the perfect birthday gift.
Anyone who's seen MTV's classic "Cribs" knows that the rich and famous love cars, and "the more the merrier" seems to be the motto when it comes to filling your garage with sweet rides. Biebs already has a Ferrari and a Cadillac Batmobile, so what more does he need? Paul at Manhattan Motorcars thinks he's got just the ticket: the redesigned 2012 Bentley Continental GTC. "Very sporty car, definitely aimed at a younger buyer," Paul told MTV News. "Completely hand-built, handcrafted in England. Just a blast to drive."
With a new ride lined up, Bieber's going to need a new pair of shades to keep the sun out of his precious peepers while he's cruising around Hollywood. For those, MTV visited Jordan Silver at Silver Lining Opticians.
"Some of the most amazing pieces I think Justin might like are Persol, Ray-Ban and some of the brands that did car collaborations in the '80s," Silver said. "One we just got in is by Maserati. It's a shield with three sets of lenses, interchangeable, and two sets of temples so that when you're traveling at high speeds you might need the extra protection of the cable temple."
The cost? A cool $1,200. But that's pocket change to Bieber's pals like Lil Wayne, who hit the recording studio with the "Baby" singer last month.
If Bieber's girl Selena Gomez is feeling sentimental about the dog they recently adopted, she could hit up Trax NYC for an $18,000 23-carat bulldog pendant. "Got some pink diamonds in the eyes. Yellow diamonds, black diamonds, all hand-set," Trax's Paul Mazza told MTV News.
For an even pricier gift, Christina checked out some of Trax's blinged-out watches. "If you look at it right here, there's a lot of diamonds," Mazza said, showing off a $20,000 watch featuring 35 carats in diamonds. "This is something that definitely garners a lot of attention. ... Got one for every day of the week, different colors. It doesn't get any better than this."
What would you get Justin Bieber for his 18th birthday? Leave your comment below!
Happy 18th birthday, Justin Bieber! Now that we've counted down the superstar's 18 greatest moments, stick with MTV News as we celebrate the milestone all day.