That’s the same price as previous weapon ornaments, but the big difference this time is that they were added to the loot pool at the Eververse cosmetic shop, meaning there was a chance to reacquire them.
By contrast, Bungie tweeted “today is your last chance” to grab the “Thornament”, and clarified in the replies that hereafter “it will be gone and it won’t be a random Eververse drop.” It’s been a divisive move: some of the most-liked replies argue that “$10 for an ornament is way too much” and “this artificial scarcity is psychological manipulation and that’s not okay.” Some players have also pointed out that Thorn is earned via an Exotic quest just like Thunderlord and Whisper of the Worm, both of which got paid ornaments which were then moved to the Eververse pool, so the Thornament seems to mark a change in policy.