Welcome on board!!!
For the budget you have you can get a decent road bike like Fuji or Schwinn. But I am not sure if you were looking for a road bike or more of a hybrid bike with thicker tires. I believe for $500 you can also get a really nice hybrid bike. If you have local bike shops (LBS) available to you, go there and talk to them about it.
When I decided to get back to biking I went and bought Honda mountain bike on amazon.com Let's just say that my younger sister is now using it to ride around the block. I then purchased new steel road bike on ebay for 150$ and used it for 1.5years before I realized I could now move on to something lighter. My steel bike also weighed about 30lbs and gave me a good training to climb those hills. So heavy bike is not so bad, it's just it needs to have all gears running. If you have some questions you can always try to search it on this forum, chances are they already been answered.
Good luck