WOW!! $1,300-$1,750??
That's double what I pay for them. The 20gauge is uncommon, but there are few if any collectors of the hammer versions, and 20s garner little if any premium from what few I've seen (2 of them).
https://simpsonltd.com/tikka-m77-z49358/https://simpsonltd.com/tikka-m70-z45406/These are better guns IMO, and this one comes with the Valmet mount, which sells for $250.00 on up.
https://simpsonltd.com/valmet-412-z49370/That Tikka you have is an Excellent gun. They are spooky accurate! I well understand why you like it.