As of January 1, our lifetime subscription has "paid for itself." When we bought our Series 2 Tivo, we had the option of going with the monthly rate or paying $250 (now $300) for "lifetime" TV listings service. Note that in this case, "lifetime" is the life of the Tivo box, not the lifetime of the owner!
I should also mention that this Tivo has been upgraded with two hard drives to approximately 320 hours at "basic" recording speed. It has a 120GB and a 160GB drive in it. For reasons only known to Linux gurus, the 160GB drive only has 137GB available for recording, but I got a great deal on it, so I'm not concerned about the "missing" 23GB.
If you have a Tivo, and haven't upgraded it, what are you waiting for? You can even do it with a Mac! When you do so, you can save your original Tivo hard drive as a backup in case something goes haywire with your new drive(s.)