Technidol doesn't really go bad, on account of the fact that it's sealed in oxygen-free packets. I've used 15 year old Technidol with good results. That being said, I picked up that developer for $6 about a year ago ($12 sticker, and 50% off for being expired), gave 5 packets away, and used the last one to develop a roll of Tech Pan I won in a contest. Now I wish I'd have waited and sold each packet for enough to make 10 gallons of POTA.