Hm. So, this reply is coming in two parts: my gut reaction as a prospective Dresden Files RPG gamemaster, and then the rulesy bits to actually address your issue. If you don't want the soapbox, skip to the part below the "***".
As written, I'd have a real problem with this character concept for one main reason: magical items are seldom easily transferred in ownership from one party to another.
Most enchanted items are only usable by the crafting wizard, and most items crafted for others are either crafted specifically for others or simply too valuable to part with. And if they're parted with, mortal money certainly isn't the medium of exchange - the supernatural world works in boons and favors and bartered goods. Often, too, magical artifacts are sponsored by an entity, like the God of Abraham and the Swords of the Cross, who simply may not like the new bearer.
Any compromise I could think of asking for keeps the character from being Pure Mortal in any fashion. He could be a Ritual Crafter who knows how to magically "claim" ownership of "found" goods (meaning, taken from the original owner's dead body). He could be an Emissary of Thoth or something, who could usurp the use of enchanted items via innate ability.
More interestingly, he could "pay" for the use of the items he gets in another way, like via a soulbinding. He finds or commissions an item that he wants. The owner/enchanter of that item can magically "sign it over" to him for a price - a supernaturally related favor of some kind, like a contract killing. He has to enact the favor to be able to use the item, and can keep it when the job is done. (I can easily think of a forest full of potential trouble aspects for such a character.)
But there's no way you get away with "I'm a rich monster hunter who buys magical artifacts" in my game. Just sayin'.
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Rules-wise, the easiest way to get at the character you want is to just take Items of Power. You say the guy can't make new items, so he's stuck with what he's got - so define what he's got and be done with it.
If you're suggesting he has a collection of enchanted items like wizards do, without actually being a wizard, then I'd just invent a custom power. Because he's not a real wizard or other practitioner, I wouldn't allow the rate that Refinement gets - my eyeball figure is -1 refresh for two enchanted item slots. And then I'd just give him Lore skill, because that's all you really need to determine effect strength anyway, right? And he's a monster hunter, so he'd have it anyway, right?
A third option is a custom power similar to Mimic Power - you "reserve" a number of refresh points to have powers available to you, with the limitation that you must predefine them at a time that is amenable to your group. They represent your bevy of items.
So there you have it.
-Lenny
