I think jaqie's guess is a decent ballpark estimate. Right now, the puppies are eating a higher protein puppy food; $33 for a 50 pound bag. We generally get those 50ish pound bags of pedigree; around $23 or $24. I just tear the top off & roll it down to the food, creating a giant dog dish. Occasionally, I'll cut off the top 6" or so of the bag to keep it near the level of the food. One nice thing about the breed is that they don't gorge themselves on food - they have food available 24/7 and are not overweight. Plus, I use automatic waterers for all the animals, so long as the temperatures are above freezing. When we go on vacation, we merely need someone to check in on everyone twice a day; I usually give them something else to do twice a day, just to make sure that they don't skip out.
Jedi: yes, they were bred to defend sheep against attacks by wolves and bears. They'll drive off a bear (I presume) - I've never seen them exhibit a fear of anything. And coyotes? They rip coyotes to shreds. Ours get along with *our* cats - but they know who belongs here and who doesn't belong here. Our friends who also have pyrenees name their cats with names like "Mcnugget" - because if the cats go in with their pyrenees, their cats become a snack.
Food bill? I don't even want to think about it. Per individual animal, the dogs are a little pricier. (Plus there are 8 of them to feed.) But, there are currently 50-some goats that get fed, plus a llama, a coop of chickens, and a handful of cats.