Why is the Black Collection sold out so fast?

I am wanting to know do they feel like the black line never sells fast enough, and add less amount's to there stock? I mean common let a sister know what's up this collection small but yet affordable than the Mac one, cannot be sold out and only the black one... Can someone but out a APB out for Foxy Barbie
The collection features four Decades of Beauty cans, each $40, with a booklet inside describing the beauty and fashion wardrobes for each doll. The first, #1 Ponytail Doll, celebrates the first Barbie, launched in 1959. It includes a red lipstick called Ponytail, a liquid eyeliner and a three-pan paper-wrapped compact with two eye shadows and a cheek color. Malibu Barbie, which highlights the doll of the same name that launched in 1971, has a pale pink Lip Glaze called Malibu, a black mascara and a compact with two eye shadows and a bronzer. Foxy Doll, which depicts the African-American Barbie launched in 1980, includes a Lip Glaze called Foxy, mascara and a compact with two eye shadows and a cheek color. The final offering, Jewel Doll, is based on the 2000 Barbie of the same name and includes a bright pink Lip Glaze called Jewel, a Multi-Effect Mascara and a compact with two eye shadows and a cheek color.