Bikes are expensive right now. What MTB do you have? Might be worth more than you think. But also the road bike will consequently cost more than you think especially for a lightweight one. If your MTB is good spec and you're looking for a trade in the. Try Airline Cycles in East Hampton or Storrs Cycle Center. You won't get a great bike for sub $300 but they should do you alright on a trade if yours is decent or they might help you find something they're really good guys at both stores.