Don't buy already made just order a piece of whatever counter you want have it installed, go to any stone company or even the big box stores but custom order.

Do you already have the vanity or are you looking for an all-inclusive piece? These two are 60" wide with stone (marble or quartz) tops in different colors, no backsplash.
http://www.qualitybath.com/empire-ds60-43-4-doors3-drawers-vanity-for-double-bowl-60-w-x-21-12-d-x-32-12-h-product-123626.htm
http://www.qualitybath.com/ambella-home-verona-grand-sink-chest-22-12-l-x-60-w-x-36-h-product-139544.htm

i already chose a vanity. so I'm just looking for the top, but thanks "quality bath". @Patricia, i just want a plain white simple top, i would think a custom order would raise the price and it shoudl be so simple to find (i thought!)

Simple I find is never easy , I would go to stone place and see if they have a leftover piece that would work, you can sometimes save quite a bit if you are alittle bit flexible about the color.