Welcome to Bike Forums.
You'll have a tough time finding a new road bike for $500. Most low end bikes start around $650.
Perhaps your cycling friend can help you find a used bike on ebay or craigslist that is your size.
Good luck and have fun.
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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.