Buying from Amazon, Best Buy etc.

Amazon
Can I just say how much I love love love http://www.amazon.com/
They often have the best deals for just about everything. To get the best price what I do is I search for the item and then below the item you will see something that says '36 new or 31 used'. Many times you can buy the item through a seller on amazon and get it at least a few bucks cheaper.
For example: Heart - Red Velvet Car.
Amazon price = 8.63. Other sellers price = 6.49. Used = 4.29.

Also if you buy something on amazon and it goes on sale all you have to do is call and tell them which item and they will credit your account. Its that simple. 
Note: You can call them more than once too if the item keeps dropping lower in price.

Best Buy
If you are at Best Buy and you see something you want to buy, check out their website first. Many times Best Buy will offer their items online cheaper than in the store. I found this out when we bought a new Sony Cybershot Digital Camera. It was about $250 in the store but I was able to get it on the website for $226 and it came with a free 4gb memory card. Also you can choose to pick your item up at the store so that you dont have to pay any shipping.

Lowes'
Before you buy that next big item at Lowe's check the other stores in the area. Often times Lowe's will sell items for cheaper prices in certain areas. I dont know why they do this but I know that often times the Lowe's at the Waterfront is cheaper than the one in Monroeville. You can do this by going to their website and typing in the zipcodes of the stores you want to check. That way you know you arent paying more for it at a different store.