FYI...
$19 for me too (from 5.4 to 5.5). But I had to ask ST as at the beginning it was $49 for me.
"Sorry for the trouble! This was due to a sync issue with our account system, but it should now be resolved. Can you double check and make sure that you are now seeing the appropriate upgrade price?"
As a special offer for May, you can get instant download access to the entire tabs database with a 50% discount!
Still ON...
But still a mystery for me ... Is it worth it? Many different point of view here ...