Buying a GadgetGet Alerts on Newer Models and Prices

Most times when we buy gadgets, we run the risk of actually buying it just a month or weeks before a newer and better version of it is released. Another familiar instance might be we buy a gadget and the prices drop only days later.
For instance, say I wanted to buy a iPhone 4, which is quite expensive. A good idea would be to wait for iPhone 5 which is rumoured to being unleashed by Apple in the coming months.
In such instances, I found Decide.com very handy; which lets users know about future models and even if price changes being expected.

Decide, allows searching for latest televisions, laptops, cameras and phones. This makes it a must for research before making a purchase.
It shows an estimated time a new model might get released and even if the prices are expected to rise or fall for the gadget. This means if you are buying something a good idea would be check if it would be cheaper say in the coming weeks.
If users want to set an alert for new model of something they like, it can be done using Facebook credentials.
What service do you use for research before buying a new gadget? Do drop in your comments.