Bostons! I have two Boston Terriers too. Mine are old farts now though.
As for the price, it all depends on the breeding of the dog, health testing the breeder does, etc. Obviously location does play a part in price, and if you're anywhere near DC the price of things is going to be a lot higher than a place out in the sticks. That being said, looking into congenital diseases that dogs can get. Hip dysplasia among other things is a big time problem in labs. Breeders who do testing on their breeding stock and have them certified, usually OFA, are breeders that are trying to breed the best quality stock for their breed and tend to have less issues. That also comes with a price tag of course.
As for the invisible fence they can work, but just remember that they don't keep other dogs that may be on the loose out of your yard. Also I have heard of many dogs that run through the fence and ignore the shock on the way out, but on their way in they won't go near the boundary because of the shock. Just keep that in mind.
