Tim — Your idea seems conceptually sound, but it might be administratively complex. One problem I see is determining the size of the carbon footprint of each good. Almost everything has some carbon footprint. How much carbon per pound of beef vs. chicken? Conventional or pasture raised? For commuters, how much carbon in a bus ticket vs. a gallon of gas? Etc. Another administrative problem is that there are more consumers than producers, so a producer-level price would require contact with and audit of a smaller number of entities. But I like your idea as a way of exposing the contribution of each person to carbon pollution.