The difference here is, you have a ranch. The OP only has 2.5-3 acres to protect. Not nearly enough room for a GP. At least from what I understand. Neighbors of ours had one. It wandered from home all the time. The owners just said, "Oh, that's the nature of the dog. They don't really know boundaries and need to cover a lot of ground." The dog disappeared one day and was never seen again.
As others have stated, a few strands of electric fence will cost you way less than a dog. Dogs are expensive. It doesn't even matter if you want a purebred or a mutt... er, "designer dog". Around here, purebreds and mixed breeds are all going for hundreds of dollars. Then there are the puppy shots, getting it fixed (either so it doesn't wander or end up having a dozen pups - depending on whether you got a male or female), heartworm pills, tick repellants, dog food, chew toys... We just got a pup last year. It's all still pretty fresh for me. Oh yeah, and the unexpected costst - like vet bills after your dog gets hit by a car when it goes on the road.
I have nothing more to add to this. Just wanted to say
Good idea! If you don't like them, why on earth were you thinking of getting one? Because you don't want to put up a fence? It's entirely your decision, of course, but a few strands of electric isn't that expensive or difficult to install on 3 acres. Shouldn't take you more than an afternoon, if that. Step-in posts, insulators, wire and a fencer, that's it. Talk to the farm supply store, and they'll be happy to tell you how to install it. If not, come back on here - lots of knowledgeable people willing to help. That's going to be your most effective tool if you're really serious about keeping those dogs (and any other strays that come by) off your place.