A Bike shop is the way to go. The bike will already be PROFESSIONALLY assembled, they'll give you Years of free tune ups and adjustments, and the Quality is WAYYYYYY Better. Something like this would be in your range. The Specialized listed would be very good as well..

 

I'm 6'-1" and weigh 220. My cheap Wal-Mart bike takes the beating I give it.

 

Guess I am a little harder on bikes than some people then.

 

Anything will break if you try hard enough.

 

This way if you get carried away and go to far then you wont die trying to get back.

 

I bought the 600DS model and really like it. No problems yet. You need to make sure you get the right size and put it together yourself, but I think it is worth it. I got a much better bike than you will find in any store for the same price.

 

I saw that model after I saw the one I posted, how much did you pay and where did you find it?

 

I got it here from this store, but look around you might find a better deal. You can save some money by not getting the rear suspension, most do not need it. Buying one of these bikes is sort of like building your own computer, it's a matter of the individual components. You need to carefully compare each component. It takes a little time and effort. Don't be in a hurry, and wait for a deal, I got the DS600 for $395.

 

Just like a fat chick, fun to ride until your friends see you!
I used to have a yellow Motobecane Moped.

I now have a Haro Vector Mountain bike. $489 though a few years ago. Only paid $300 for the moped.

 

I used to ride bikes a lot, both road and off road. My advice is to buy the best bike you can possible afford. The better the bike, the more fun it is to ride, and the more you'll ride it. In my mind, it is simple as that.

 

You arent gonna get much for $300. You are pretty much looking at a bike with no suspension and cheap components.
Heres what I would go with: http://www.trekbikes.com/us/en/bikes...0_series/7000/
The frame is made in Taiwan, but the bike is assembled in America and the company is American.
I personally ride a '97 Cannondale Super V 500 (full suspension and VERY light), but thats waaaay more bike than you are looking for.