Personally I think we should charge the maximum the market can offer. However, I think this is a difficult number to determine. Looking at the social cost of carbon table (EPA), I would opt for the most expensive number determined each year. In 2015 this was $120. However, I think perhaps we could make the prices self-regulate. Australia has created a national water market (http://www.nationalwatermarket.gov.au/) which serves as a water reserve. “Having a market that everyone has access to, no matter how much money or land they own, means that there is an equilibrium that occurs naturally within the market” (Peterson 2015). I think this could be adapted. Require government to set allocated carbon use each year. So every year some people might sell their carbon stocks to the government, thus reducing the overall available stocks. Also allowing companies to trade carbon stocks with each other. Alternatively, perhaps prices could be set auction style. Every year the government says we have x amount of carbon, which will be auctioned off in blocks, the bidding begins. This would also have the added benefit of creating more money for the government which could then be pumped back into other funds