Consider 200$ for the budget and 50$ for tools. With basic items like cable cutters/crank puller you can assemble a better bike for less. The best quality builds for the money are Nishiki or Univega. They are common brands. Centurions are also good to look out for. Sometimes that 250$ complete bike on craigslist is nothing more than a good rolling chasis. Why pay more for parts bike?