1) you're right that opening up into the pedal space is cheaper and 2) there's a ton more variety available in that space (both of which are interesting facts, I wonder why that is).
-- troux
there are loads more guitarists in the world than modular synthesists...
market bigger, production runs potentially bigger... cheap pedals are made from cheap components - thin metal or plastic enclosures etc etc circuits are often incredibly simple and small...
interesting/innovative pedals from boutique manufacturers are in the same ball park as modules -
as are rare out of production cool pedals - some can get very expensive - moogerfoogers, lovetone, klon etc etc
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities