These Palette [sic] Coasters by Labyrinth are available at Design Boom for $21 (for a set of five). However--you knew this was coming, didn't you?--I'm thinking they are totally DIYable. Most of the cuts could probably be done with a utility knife, considering the thinness of the material. To order, head on over to Design Boom.
P.S. I know, 'palette' should be 'pallet' (thus the 'sic'), but that's their name at Design Boom. The designers are from Spain, so maybe it's a translation to the English-speaking market situation. However, considering the interesting etymology of pallet/palette, perhaps 'palette' IS correct for a Spanish-speaking person.