[2022] I’ve had this for a while in my closet. Any idea how many of these exist? Collector’s Edition Signed by dev team.

I see mine! :D

As for how many, it's hard to say but there are a couple varieties of signed ones:
1) The set that we all signed en masse, one for each dev employed at launch - a full room of them! (some of these have made it into the wild and I suspect this one is one of those due to the density of signatures and the presence of my signature).
2) One offs that sat on a table in the common area periodically to get signed as people walked by. These were often for giveaways, later hires, etc. (resulted in fewer signatures but more likely to be found in the wild)

edit: just saw the other comment saying this was won in a radio giveaway. Knowing that, this was probably one of the earlier one offs, but it's also possible there were extras from the initial mass signing.