-Staple Gun (mine is an Arrow brand, model JT-21M, and JT-21 8mm staples)
-Cotton duct canvas (Fabric stores sell it pretty cheap, tent/awning manufacturers will sometimes give away scraps. If you are looking for a real bargain pick up some canvas "painter's drop cloth". Home Depot sells 12 foot wide ones for about $15. It's not good quality, but it works great for studies and stuff once it is primed. Art stores have the best kind but they will charge you a lot more for it).
-Stretcher bars (I like to get the thicker bars. If the bars are too thin, sometimes the canvas can warp once it is stretched. Thicker bars don't have that problem, and as a bonus you can get away without framing your painting by painting the edges)
Some people like to use some kind of canvas-stretching pliers. I find that I can stretch it tight enough with just my fingers. Any creases left in the canvas will go away once you paint the gesso on (gesso shrinks when it dries). The canvas will be as tight as a drum if you do it right, so I don't really see the need for any extra tools.
Here is a set of stretcher bars. I believe it is Utrecht brand. I decided I wanted to re-stretch the canvas so I removed the old painting and the staples. The stretcher bars are upside down on a piece of canvas, and the canvas was cut so that there is about 3 inches extra all the way around. Try to center the bars as evenly as possible.
Then I prime them with 3-4 coats of gesso followed by a light rub of sandpaper. Make sure to gesso the edges too.