carnivorous plants of the world -- unite!
Don't know of any supply shops particularly for CP enthusiasts. Depending upon just what materials you use in your media, you might consider hitting an orchid show. There is one vendor I know of at such shows who does sell various component materials for making one's own personalized media. For some component supplies, I believe folks will hit places like Lowes. For something like live sphag, you can hit the reptile show in Taylor or try getting ahold of Travis (aka "Mass"). He's a cp'er in Lansing and I know he occasionally has sphag for sale.
"Blessed are the cracked….
For they are the ones who let in the light."
"occasionally".. means whenever we're not buried in snow.