I would discourage you from buying a Next, Huffy, or Roadmaster. These bikes start squeaking within months, and aren't very good quality and are worth at most what you are paying for them.
A new Schwinn or Mongoose are more expensive but are much higher quality, I bought a Mongoose 7 years ago and it is still my main riding bike. If you are willing to look for a used bike craigslist would be an excellent place, you can often get a good quality bike there for around $100, which new would cost you around $200.
Good luck shopping.
