Where can I find a decent priced photography camera?

I'm looking to buy a photography camera and of course my first stop is a Nikon as I do know they are as expensive as all get out. I'm very big into nature and historical site photography and have an eye for just about anything. I want something that will best compliment my work this is just for my satisfaction but I'm very passionate about it. Price to me is just a bit scary because I'm a full time single mother and student so saving isn't a piece of cake but I'm willing to hold off on new things in order to save up.
Well now that I'm done sharing my life lol Where could I look for a camera that is worth the money and possibly comes with a warranty (so i'm more at ease when purchasing it)?
Also, one I have the camera would it be ok to buy used or refurbished lenses to save money?

When you say nature, this covers a wide ground. If you're doing landscapes or flowers, nothing special here. But if you want to capture wildlife -- the most challenging being birds in flight -- you're going to need an expensive camera and a long, fast lens. That's thousands of dollars worth of equipment. If that's not your major interest, then you can get a good point-and-shoot camera that will serve your interests. It's a highly competitive field. So prices are driven down and you get what you pay for. If you don't buy the cheapest one, you will get a camera that has the ability to take very nice pictures in most settings. Your best tactic is to go into an electronics store like Best Buy and hold the various cameras in your hand. Pick one that feels right. Do not believe the salesperson when he tells you that more megapixels is better. It's not. 10 is all you need. And that's about the lowest you will be able to get. More than that will give poorer results in low light settings.

Others will tell you to get an entry level SLR or perhaps a micro 4/3 system camera. They're fine cameras. But, except for the bird in flight thing, at your level and with your interests you'll do just as well with a quality point-and-shoot.

Just so you know, I've been a photographer for decades. I have two SLRs. But I also have a point-and-shoot as a walk-about camera when I don't want to bring along the big guns.