I agree that 50 million would be a little high. That is the going rate right now, though. And people pay it. I've seen 2 sell this last week. One was an item blessed bracelet, the other was the deed itself. However, there is a big difference between something that 2 people are willing to buy in Luna, and something that thousands of people would buy.
How about this: Production shards only: Armor bless deeds as a rare reward for high-end blacksmith BODs, weapon bless deeds on NPCs for 15 million gold, and item bless deeds as part of a new, yearly spring cleaning event?
When you're paying several million for a bless deed, buying one is NOT to avoid paying insurance. It's to prevent accidentally letting insurance lapse on a treasured, irreplaceable item. Like, for instance, if you've burned through 15 valorite runic hammers and finally made the perfect weapon. Or if you've found the perfect ring or bracelet. You're not going to pay a fortune to bless something mediocre when you can just pay 600 gold to insure it. I would probably buy a couple of armor bless deeds for favorite items if they were in the 5 to 10 million range.