Value should be around the same as an angel adjusted, but probably you wont find seller for that price.
FEN is +5 stab and cut, but no 12 electric on it, i would consider it about the same level and price.
Tier upgrade on FEN is about 75% of the adjusted, so high tier should be even cheaper on FEN.
FEN is just rarity.
You can overpay it if you want that FEN name on your armor so much, but probably much reasonable to buy adjusted angel.