Get a good name brand from a local bicycle dealer. A bottom of the line Trek, Specialized, Giant, Salsa, etc. Is going to be far better than Walmart, Dave's, Dicks, etc.. Also you can get it fixed and tuned up. You don't just through them away. If you have a good bike you will enjoy it and ride it more. It won't just be a waste of money. I bought my teenage son a $1000 Specialized fuse. He has thrashed that thing, and it is now a buddy bike. It just won't quit. I do most of the maintenance and any difficult repairs are relatively cheap. I have invested thousands in bikes. Literally! If you have any questions ease ask.