I've been developing a price tracking website at https://www.pricewombat.com. It's still in beta, but I believe it works better than PoachIt did. One of the main advantages is that I've made it so that it compares prices across retailers. So instead of tracking a product price at just a single retailer, the site tries to track products at all major retailers. It's still a work in progress, but I'm hoping to launch it within the next few months.