Actually, using Red Dragon blood would be considered a Power Component (Page 96 of the DMG), and thus circumvents the XP cost.
If it were me, I would not require flaming swords blood for Red Dragons. Red dragons should be rare things, not 'the hinges you need to make a door'. Otherwise, Red Dragons would hunt down anyone with a flaming sword.
If it were me, I would not require flaming swords blood for Red Dragons. Red dragons should be rare things, not 'the hinges you need to make a door'. Otherwise, Red Dragons would hunt down anyone with a flaming sword.