For $500 you should be able to put together an outfit you can use for the rest of your life. I think 45 @ 28 is an excellent weight. Depending on what you plan to hunt, you may never need anything else. The classified section here is a great place to start. You should be able to find a suitable bow that you'll be proud to own and show off and still have plenty of money left for your choice of quiver, an arm guard, a tab or glove, and a dozen arrows.
I am shooting Beman ICS Bowhunter 500 arrows now. They are inexpensive, tough, and easy to tune. They should work fine with a 45 pound bow. They shoot great from my 46# Kanati.
Welcome to the fold. This is a great place to learn. Feel free to ask questions. As has been said, this quickly becomes an addiction, so your first bow probably will be just that.