Nice article, it goes over 5 different price tracking tools, 2 that I use. CamelCamelCamel I have used for years and same with slickdeals. But Invisible Hand, CheapShark, and PriceZombie are new too me. Actually I think I have heard of Invisible Hand before. I like the sound of PriceZombie so I will be trying that out soon.
http://lifehacker.com/five-best-price-tracking-tools-1692745053