For the old timers - CT will display your cost AND and a current valuation based on info from WineBid.com. You can switch this on and off in your account settings. The determining factor would be how much original cost info that you put into CT when you signed-up.
For my humble and obviously young cellar, average cost per bottle: $27, average value per bottle: $31
I don’t have a clue. We have some wines still in the cellar that we acquired in the late 70s - early 80s, with a very different price structure from today. Today’s purchases possibly average close to $100 per bottle.
For the number to be meaningful, you’d have to factor in when the person started buying. If you started buying in the last couple of years, you’ll have a high average. If you started 10 or 15 or 20 years ago, the figure may be a lot lower, but you might have a lot better collection.