Floating Value?

Would it be possible to either customise the plugin myself, or have it added to the plugin by yourselves, to allow the value of the virtual currency to ‘float’ on an hourly, daily, weekly or other time period basis, based on trading between users of the currency? So I plan to have a marketplace where people can buy or sell goods and services and pay with the virtual currency, but also have a separate section where the currency can be bought and sold for real money, with options for sellers to either sell at the current exchange rate, or for a higher or lower rate, or to negotiate with a buyer. We also plan to have a commission on these trades. The plan is that at the end of every day, a new exchange rate will be set based on the trades that day. Obviously this could be done manually by calculating it and changing it in the settings, but equally obviously it would be much better if it could be automated. We only plan to have the exchange rate against one currency, with any other currencies being based off that. Incidentally we also want to have this exchange rate prominently displayed in the currency trading section, and probably elsewhere, so any advice on that would also be welcome. I appreciate that this could be quite complex but any advice you can offer would be very appreciated.