Pyrenean Mastiffs can cost you anywhere from $1,000 to $1,800 depending on the breeder, but show quality Pyreneans can cost at least $3,000 to $5,000. Average annual expenses to keep a Pyrenean Mastiff can also run you up anywhere from $1,500 and up. The costs are relative to the size of the dogs, especially since they eat quite a bit and ...