TPMS Battery Life - Know Before Buying!!!

In recent months the market has been flooded with replacement TPMS sensors for all makes and models. It seems that the price of these varies greatly from vendor to vendor. I have recently also noticed that the OEM parts distributors i.e. Ford, GM) have started "dumping" old stock into the market as they have realized that the parts do have a shelf life. Most sensors will last from 5-10 years during normal service on the vehicle, however it has been proven that the battery life still degrades while the parts are in sleep mode on the shelf. I would suggest to buyers that you ask for the production date of the parts before you purchase as you may be losing up to 50% of the life of the parts by buying old stock. These parts are not cheap so protect your investment. Most larger distributors will get "fresh" stock more often than some of the discount retailers. I have seen this a lot on Ebay and Craigslist where the vendor is not recognized by the manufacturer. So as usual, buyer beware.