WTS: Bicycle for exercise

[Taurahe]

I need to lose weight, so i am looking for a bike for exercise. i am looking for quality bike that is in good shape. If it needs new tires, thats cool. If it has been sitting on the side of your garage for 4 yrs, im not interested. Trek, giant, marin, dimaondback, cannondale... you get the idea. Not interested in anything that comes from Walmart, no cruiser style bikes, no bmx. I am specifically looking for a flat top for commuting and fitness riding. not really looking for a road bike, but if the price is right i will consider it. Looking for something in the $200-$300 range, but i have more budget if it really strikes my attention. Older is fine with me, so check your garage. i would prefer thumb shift but im not going to get too picky. I am 5'9", so looking for something in the medium to large frame size, depending on manufacturer. If you have one to sell , shoot me a pm please.