I researched and planned for many months before purchasing my Canon 40D SLR and lens. Along the way, I got a feel for a few things to do and not to do if you want to get the best deal possible on a new camera.
The best prices are with online retailers. Brick and mortar stores simply can't compete with the low overhead of an online retailer. A few good choices are Adorama, BHPhotoVideo, and Amazon. My favorite is Amazon, and this is who I chose to purchase my camera, lens, and memory card from. Amazon offers very affordable shipping and a large stock of cameras in stock. If you are looking for a popular body or lens, odds are that Amazon has it in inventory and ready to ship.
For newly released cameras and lenses, Amazon offers pre-orders where you can get on a list to have the item shipped on a given release date. Your credit card will not be charged until the item is on the way to you.
Amazon offers a generous return policy; you have 30 days to try out your camera and send it back if there is a problem. This is very important buying a camera sight-unseen. Amazon is very impersonal by nature, but this can be an advantage when sending a camera back. No sales person to deal with or try to stick you with another camera that doesn't meet your needs. You simply start the automated process to get a return label and ship it back.
One thing to watch for with Amazon - if your Canon lens or body is not in stock, it might be sold and shipped from another retailer working under Amazon, called a merchant seller. If you purchase from a merchant seller, you will be subject to their return policies and will need to return the camera or lens directly to them. This is not the best and I avoid purchasing from a merchant seller if at all possible. You can tell it is not direct from amazon when viewing the item - toward the top under "In Stock" it will say "Ships from and sold by (name of retailer)".
Actually, Canon SLR bodies and lenses are very stable in pricing for items that are new. You won't find "sales" in the usual meaning, but Canon does periodically offer rebate programs. The rebate programs often require you to send in proof that you purchased from an Authorized Retailer, along with some paperwork, and wait for your check back.
Alternately, Canon sometimes offers "instant" rebates, where the price is reduced immediately when purchasing from an authorized dealer. These are the best kind and what you want to wait for. Rebates are usually not offered on brand new bodies and lenses; however, they can apply on models at the middle to end of their life-cycle. Rebate programs are announced on Canon's website.
Know that if Canon releases a new and shiny camera model, the prices will be the highest initially and will drop over time. The life cycle for a digital SLR camera body is about 18 months between the time it is released and when a replacement is released. In this time, the price will remain close to peak for the first 1/3 of its life. At around half to 2/3 of the way through the product cycle, the price will often drop dramatically, sometimes with up to 30%. If you can resist the urge to have the latest and greatest, you can save hundreds by waiting only 6 to 9 months for a drop in price and a corresponding rebate program.
Lenses have a longer life and therefore are more stable in price. Lenses are included in Canon's rebate program, so be on the lookout - lens rebates are usually $50 to $100 off and in conjunction with the purchase of a Canon body.
Really, Canon's pricing is generally controlled and it is simple to get a good deal. It hinges on taking advantages of any rebates offered and being smart about waiting to purchase after the demand and price goes down. Also, your best deals will not be found in a store - look to online sites like Amazon.