I use the variant found in Player's Guide to Wizards, Bards and Sorcerers (S&SS). There are different sized spell pouches that can be filled with "spell component units". If a spell component doesn't have a cost assigned to it that component uses up a unit. If a spell component's cost is 1 gp or more, then a unit won't do it and you actually have to inventory these components.
The new spell listings in the PHB 3.5 are very handy for this use, since spells have an "m" marking if their casting requires a spell component that is more expensive than 1 gp (for the use of Eschew Materials feat, but it also serves this variant very nicely).
The new spell listings in the PHB 3.5 are very handy for this use, since spells have an "m" marking if their casting requires a spell component that is more expensive than 1 gp (for the use of Eschew Materials feat, but it also serves this variant very nicely).