I don't find that a group making a grocery list is any more exciting than one person doing it personally.
The 'grocery list' as you put it isn't the fun part. The 'shopping' on the other hand, can be a blast. Or several of them.
Something which people seem to overlook, at least from my perspective, is some of the background work which goes on 'off camera' between the various novels and short stories in the Dresden Files. While some players and GM's could just gloss over some of that, and they should for much of the more mundane and/or boring stuff, Jim Butcher glosses over some areas which could be quite interesting, but aren't particularly relevant to whatever story he is telling at that particular point, and below are three examples.
The first is from Grave Peril, right in the beginning Harry has a charm which he made and has been using to provide him some protection from the ghosts and spirits that he and Michael had been fighting, immediately before the start of the novel. Now I don't have the book immediately in my hand, but from memory it included things like a dead man's shroud, blessed silver, and other things which were harder to get.
The second example is also from Grave Peril, but it also gets mentioned in Changes and might have made an appearance in other novels and I've just forgotten. This one is ghost dust, which is basically a specially enchanted material for use against ghosts and other non-corporeal entities and the base material it is made from is depleted uranium amongst other things.
The third example is a very special bullet which Gard prepared for Marcone to use and was mentioned in Even Hand. The bullet was inscribed with a rune by Gard, but it apparently had to have been a 'special' bullet for the rune to be inscribed and effective. What made the bullet in question so special is that it was a bullet which Gard had either taken out, or got right after it was taken out, from the British admiral named Nelson that it mortally wounded. Incidentally, and to provide historical context for how important/rare the bullet used as the base for the rune is/was, there is a statue of Admiral Nelson in Trafalagar Square, commemorating his victory at the Battle of Trafalgar, as well as the death of Britain's greatest naval hero in the naval battle which broken the naval power of the combined Franco-Spanish fleet during the Napoleonic Wars, and the last fleet battle the Royal Navy would have for ~110 years until the Battle of Jutland in during World War I.
Given the role and importance some of the items I've listed can have, as a GM I would find it absolutely appropriate to have the players spend a session or two just trying to gather the more important and rare materials for a major ritual working. I freely admit that some of the materials I'd allow to be gathered by creative uses of the Resources and/or Contacts skills, but for some, the story associated with just getting the material would make it worth doing. Otherwise the Dresden Files RPG which has always struck me as being more of a story-telling RPG, becomes little more than a roll-playing game and not a role-playing game.
-Cheers