My husband started ours this morning. It is very similar. we have an 8x12 platform base that he made out of some lumber and pallets. He used the really thin plywood since the pallets are under it and painted it with a mis matched waterproof paint like chiques chicks said to do (about $5 at lowes). The back is going to be 1 pallet tall (4 feet ish) and the front 6 feet with a door etc.
I believe he spent about $150 at lowes but our front wall isn't made of pallets. if you use pallets for the front you could save more money.