It depends on the rarity and supply of the item. I recently saw "Dragonoir Familiar" in a Item Megaphone in Scania going for 6 bill.How much is this thing worth "Dragonoir Familiar", I just got it from opening a "Legendary Booster Pack".Yes you are required to be it's level. You can register it into your Codex, but you won't be able to summon it until you reach the requirement.
It's say "107", does that mean I have to be level "107" or can I use it right-away?
Update. I manage to check with the owl, is it really worth 8b? - Only saw one person selling it for that price.