It's about the size, and materials you use. Basically, we built Fort Coop. We bought it all also, and ended up at about $1,000 without counting the automatic chicken door.We just bought all the material to build our coop and my husband thought it would cost less, so I'm just curious if we overspent or if it was a normal amount($550ish). We didn't have any access to free/cheap lumber so we had to buy it all..