You Need It To Do
After you've done your research, you should read some reviews and make sure that your potential camera isn't a lemon. Go to Google and search for the camera model and review.
Read through them, but pay attention to who the reviewer is. Are they honest? Do they have anything to gain by giving a good or bad review? Some unethical people have put up fake reviews with links to the products.
These people make a commission on every sale. You want to watch out for them. Sometimes, they've never even tried the cameras they're "reviewing".
An especially good place to look is on vendors' sites. Sometimes consumers who have bought that model from the vendor will post their reviews. These are usually genuine. Just snoop around and you'll find some.
Probably the best thing to do is just read lots of reviews online. Eventually, you'll find a trustworthy review site that you can return to again and again.
To find good deals you can try sites like Froogle. Find them at froogle.google.com. You can search for products here by brand, price range, store, etc.
If you're willing to buy something used or refurbished, you can search on Ebay. Just try to figure out why the person's selling it. Is it a lemon? Or are they just no longer interested in digital photography? Maybe they've upgraded to a better camera.
Finally, make sure that you get a warranty or a money-back guarantee. That way, if you have any problems, you can get them fixed.