particular board was an accessory offered with the sink; some companies like Blanco and Franke do offer these boards which are made to specially fit their own products, so you could try checking into that first.
Other than that you could possibly try here: http://www.eastbayfurniture.com/ they have made
individual boards is more authentic, though, and some people don't mind the small amount of shrinkage.
This is a standard offering at our local lumberyard - the spacing is 2", but it comes in several sizes. This is a plywood paneling type as opposed to individual 6" T&G boards. Check your local specialty
Larger beads, possibly PVC for durability, all the way to c-top