If you know what size bike you need then either craigslist.org for good quality used or bikesdirect.com for new.
http://www.bikesdirect.com/products/road_bikes.htm
If you don't know what size bike, ask a cycling friend to help you or visit a bike shop.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.