It is now possible to send trades that include Chicken Dollars, so you won't need to buy things from the store for people anymore, you can just send the C$ over directly .
By default, people can't send you trades which ask for your Chicken Dollars. If you want people to be able to make offers on your Chicken Dollars, you must turn that option on in your Trade Settings. The other person doesn't get to see how many C$ you have in total.