What Breed/type Of Dog Would Be Good For Me?

Alright so I know It’s Summer 09′ but next Summer I’m supposed to get a dog! Alright, well I’d get it at the end of June so over the Summer I could train it, walk it, spend time with it, let it get used to me, ETC. Well I need to know also what dog would be right for me because I’m at school 7 hours of the day. And it HAS TO BE a dog that does not bark a lot. Right now I’m kind of looking at a Jack russell terrier.
Like this: http://www.breederretriever.com/photopost/data/511/medium/jack_russell_terrier_roux.jpg
I need help! But when I get one, I’m just going to search free dog/puppy, and whatever come’s up. As long as it’s a small dog/that’s already house trained, that is NOT a chihuahua. Than I’ll probably get it… HELP, PLEASE AND THANK YOU
And as I said, I want a free dog. It DOESN’T HAVE TO BE FREE, I’m not pooor. I can spend $100-$250. I just want a free one, so it’d be easier on all of us.
I’m not asking if a Jackrussell is good for me, but WHAT TYPE OF DOG IS GOOD FOR ME? Cockapoo, Chihuahua Pitbull, Boxer, what?
And it HAS TO BE a common dog. Not a Cavachon or anything, because they don’t usually sell those/they’re rare. It has to be a common dog people sell on regular basis.
+++++++ I was looking at french bulldog’s/boston terrier’s, I really liked those! But I heard they have high medical bills, and when they do have problems is it often? Or only certain dogs. Please help!!! Thank you so muchhhh