...I'm editing it a bit for presentation purposes:
"An issue that could be a problem is with material components. Fate and SoTC kind of hand-waves the concept of equipment. It is generally assumed that a character automatically has their tools-of-the-trade (although Diaspora has Wealth/Resource rolls with stress and consequences for buying stuff)."
Example: A pinch of sulphur for a Fireball sounds like something any Wizard with a Fireball spell is likely to have on hand and doesn’t really restrict the casting in any way.
"Have you thought about how you’d handle spells that have material costs - 2500 gp worth of this-or-that? Will you just tack on a gp economy?"
I'm so thrilled that I'm getting the chance to have this kind of dialogue. These questions are really helping clarify issues in the SoG rules.
Your points about Material Components are very valid.
I agree SotC does gloss over money, and I've been putting some thought into a "ladder-based" wealth/treasure system in the hopes of doing "Fate treasure" without having to be an accountant. However at the moment, I'm not firm on anything. So I can't really give a good response to the economy question right now.
Now, thinking back to economy, magic reagents and the source material, I don't remember playing in ANY old-school D&D games where the DM got very granular at all around restrictions on the V,S,M components for spells. The impact of expensive components (and having them handy) was usually indirectly handled, if not outright ignored. YMMV.
In fact in all my years (gawd, that makes me sound old) of tabletop playing I only remember once when it became an issue at all. It was one of the few times I played a magic-user PC and we ended up on a weird tangent because the party wanted me to cast an "Identify" spell and the material component was swallowing a live goldfish. So the adventure went on this whole sub-quest because I needed to FIND a live goldfish (they weren't exactly plentiful), and carrying one around was a big pain (keeping it alive) and then I wanted extra treasure because swallowing a live goldfish was gross, etc, etc... Oh, the good old days! :)
The example you stated above about having a pinch of sulfur, or more generically about material components that might be mundane or fairly common is a good one. And as a GM, I probably wouldn't bother with trying to compel that too often. But understand that it's available and given the tone of a particular game, might be fertile story-telling ground.
So with the understanding that Fate is about story-telling (and so am I), I want the SoG implementation to support my stories, rather than get involved in resource management. Lemme throw out some possible examples as to how I might (as a GM) use the Material Component restriction...
Certain spells require "Very Rare" components, but the Wizard has the aspect of "Penniless Wanderer". The GM might compel the "Penniless Wanderer" aspect and restrict the player from being able to cast spells with a "Very Rare" material component requirement. The player could then opt to resist the compel and perhaps state that having acquired those components is the reason the Wizard has no money. (With all the attendant Fate point gains/losses)
This same scenario might also explain why an otherwise "bookish" Wizard might go off adventuring or attempt some other fool's errand--to be able to purchase these components and thus be able to use those spells. Or stated in Fate mechanics: GM compels Wizard's Aspect "Penniless Wanderer" and thus the Wizard goes into the sewers to find out why the Baron's men are going missing and thereby claim the reward.
Wizard acquires a decent chunk of treasure, and the player might gain an extra Fate point by stating he's blown it all on expensive reagents and is now penniless again.
Party is splitting up treasure, and GM compels the Material components aspect to force the Wizard into either not being able to cast those spells in the next adventure or (better roleplay opportunity here) negotiating with the rest of the party for a bigger piece of the pie: "Do you KNOW how much that fight with the Lich COST ME?? So your armor's dented--big deal! I'm out thousands of gold!"
In the middle of a dungeon, a player short on Fate points (and with Wizards, that's VERY possible), tags his rare material components aspect and decides to spend some time slowing down the party by rooting around in the innards of some monster the party just killed, because "do you know how much Umber Hulk bile is going for these days?"
(Any GM worth his dice is gonna have fun taking advantage of that)
Literary example: "Harry Potter and the Half-Blood Prince" Professor Horace Slughorn "harvesting" spider guts from Hagrid's recently-deceased pet. That was pretty indelicate, amiright?
Bottom line: For gameplay, I don't know that I'd be beating the material component requirement over a Wizard's head. Only that the aspect is available to use to help tell stories and provide roleplay opportunities. As a general guideline, the more rare a component is, or the more spells the character has access to that require increasingly rare stuff, the more likely I would be to compel/tag them.
I think it depends upon the tone of the game: some games might never bother with it, whereas other games might use it pretty regularly.
It might also provide an additional motivation to have the Wizard aspects and whatnot progress over time to address those kinds of issues.