I was in a very similar situation when it came to bikes not that long ago. I purchased a store brand bike because I wanted to save some money. I ended up not riding that much because it wasn't enjoyable. I ended up literally giving the bike away at a garage sale I disliked it so much. After a stop by my LBS where they fitted me for a hybrid I found out how much fun cycling could actually be.
I second the suggestions for looking used at your lbs and on craigslist/ebay. I myself am selling my trusty hybrid on Craigslist now in your price range so that I can upgrade to a new road bike, so the deals do come. You may just need to be a little patient. Good luck with whatever you do.