This is very useful feedback. Here is a proposed rule to address your concerns:
Substitute Special Components: Finding the right special components for a ceremony can be a challenging and time-consuming endeavor. Eldritch power is, however, fungible on a metaphysical level. This fungibility allows a ceremonialist to substitute alternative special components of the same total gp value for the unique special components required for any given ceremony. Since it is more challenging to tap the energies for the ceremony in this case, the ceremonialist suffers a -1 penalty per level of the ceremony on his Ceremony Throw when using subsitute special components. Merchants such as curios dealers, herbalists, and antiquarians will sell nonspecific special components (such as spider webs, plant roots, crushed ivory, and so on) for 1gp each, in various markets, subject to the usual limits of equipment availability and commission.
Why this addresses the problem:
- It imposes a very minor penalty on low-level ceremonies but an increasingly severe one on high-level ceremonies. You may risk using the "generics" on a 1st level spell but not on a 6th level one.
- By setting the price for generics at 1gp and stating that the "total value" has to equal the special component cost, it allows for them to be widely available even at low-class markets. A Class V market like Turos Tem would have 30 x 1gp worth of components available and 30 x 1gp x 10 = 300gp commisisonable per month. That's enough that a low-level ceremonialist could do quite a few ceremonies before running out.
- The escalating penalty implicitly justifies why subsitute components don't work for magic research; the penalties would be sky high.