Well, as a matter of fact, she is one of the most famous rap singers in the US. And you should know she is known for her various stunning wigs and contact lenses. Anyway, there is a clue that you can see what brand of colored lenses she chooses,http://www.millionlooks.com/shopwindow/the-new-fashion-accessory-coloured-lenses/. There are many places where you can find those types of contacts, generally they would not cost you much, maybe within 100 dollars.
It is the doll contact lenses that nicki minaj wears. If you want to buy one, you could go to the near eyeglasses stores to buy one. If you want to spend the affordable price to buy one, you could go to the reputable online stores, like visionwork, walmart and so on. The quality there is good and the price is suitable.
Actually Nicki Minaj doesn't list her eye color in her profiles, but are said to be brown. She usually wears a grayish blue pair of contact lenses as being seen on her "Super Bass" music video and "5 Star Chick Remix" video. She wears Kuwaiti brand contact lenses Classy. Getlenses.co.uk have an assortment of great lenses on offer.