I don't know if thats worth that much gold...
You've obviously had little experience with trinkets. This is the best out-of-multen-core trinket for a mage or priest. In fact, I don't know if there's a better one that drops in Multen Core or not.
100% Mana Regeneration is awesome when you have 330 Spirit. That's about 100 mana a tick, 15 seconds @ 100 mana / tick = 800 free mana. That's almost 3 Flash Heals regen'd while casting. It's an amazing trinket.
Besides. I already have my Epic mount, Edal'Thedras seal and my 200g enchant (+55 Healing Spells). What else would I want that I can buy with gold?
Plus...