How much does a great Dane or irish wolfhound cost?

I love giant dogs but have only ha a coonhound at the largest. I'm trying to convince my dad to let me get one of the two breeds. Which is more of a one person dog? How much does it cost to feed them daily? How much do toys cost for such big breeds? Can they live outdoors/ in the garage. I live in ky but it doesn't get super hit where I live. I have a kiddy pool I can fill with water for them. I spend practically the whole day outside. Only going in to eat or sleep. I'm homeschooled so I live at home. I'm also looking for a dog that will go for 2 mile walks with me daily. I've heard the great Danes are couch potatos. Would they keep up? Also which is easier to train? Any information you could give me would help out alot. Also which gets along better with other dogs? We have two small/medium dogs that have never snapped at another dog and are really friendly. They welcome anyone into our home. If a burglar came they would show them the jewelry box. Lol. Thanx if you can help me out.