$100.00 an hour!!!
Sometimes local rescues or shelters run obedience classes that you might check into. I am not impressed with what PetCo and PetSmart offer as far as trainers. I doubt very much they have any experience training dogs for obedience trials.
Your best bet right now is to wear the little guy out. A tired puppy is a puppy who is not out looking for trouble. Maybe you could find one of those small tennis balls and teach him to fetch. It's a great way to exercise them when the weather is to hot or cold outside. Just don't leave the ball to play with because they like to chew those things apart. Keep working on his sit and maybe you could add 'down' once he gets good at sit. I know how frustrating it is at first but it will get better.