OK, lets start at your stocker wheels and tires. You can get a set of those on eBay for about $600, they are called take offs. Basically a wheel set that a dealer or wheel and tire shop took of a car to put aftermarket stuff on. They flip the stock wheels for pretty cheap. For your case it depends on if you want to sell the tires with it too. I don't know the condition of your tires, but I would say you have about 4,000 on them? That $500 is good for just the wheels but who would want wheels without the tires. So, with tires I would say about $750ish maybe $800, depending on condition and milage.
Now for some aftermarket wheels. You would start with what diameter you want, I personally like 19" on these cars. Stick with 18" if you want a little more comfort to you ride since you can fit more side wall tire in there. I have seen as big as 22" on these Camrys; its ultimately up to you. Search the site for pics on different sizes and how they look, they are all over.
Once you choose a size then you have to take into account a couple of things; are you going to leave the stock suspension, put drop springs, or put coilovers. When you put wheels and tires on that are any bigger then stock it make it look like a 4x4, so a drop would be nice. Suspension will dictate what width and offset of tire you will get. Stick with stock suspension or a drop spring, you can get a wheel that is 1-2 inches wider then stock. Get coilovers you can go as much 3" wider over stock wheel width.
Wheel width and wheel offset go and in hand. With offset the higher the number the more inward the wheel will move, toward the strut. The lower the number the more outward a wheel will move, toward the fender. Example, you have two wheels, 8" +40 mm and 8" +30 mm. The 8" +30 mm will stick out more toward the fender then the other by 10 mm. There are many calculators and tutorials on the web to figure out offset vs. wheel width; TireRack.com has a pretty good one. Just so you have a starting figure, your stock wheels are 18" x 7.5" +45 mm. Earlier in this thread I put how to figure out wheel width and offset so you get a good fitment.
For tires, it would depend on the wheel width you get. There are many pictures and suggestions on the internet on what tire sizes fit on a certain width wheel. Then you have certain looks and ways to fit larger wheel widths by adjusting the width of your tire. A lot of VW, Audi, BMW, drift Nissans, and drift cars in general will do this. There is a stretch look to the wheel, fitting a skinny width tire on a wider wheel. This will help the tire to clear the fender and not rub. Again, internet has a crap load of pictures and suggestions.