Hot Chocolate for sale

Mike and Matthew are in the process of building their Pine Wood Derby car for the big race this weekend. Oooooh, Matthew designed an amazing car, built for lightening fast speed. They have spent two nights at the Hobby Shop (one of the most amazing places on the face of the earth for a 5 1/2 year old boy) working on their car. All that is left to do is paint. That's where they were last night. That's where they were when Matthew discovered the new amazing truck that he fell in love with. It must be really amazing because it costs $250! When Mike explained to him that $250 is waaaaaaay too much money, Matthew decided he would just make the money himself. (Reminds me of when I sold my drawings door to door to make money for a stuffed unicorn from the Hallmark store). He's going to sell his old toys. At first he was going to put up a table in the yard (on the coldest day of the year) and sell his toys. Mike then explained that those types of sales are only successful if it's nice out. So then Matthew decided that he would sell his "customers" hot chocolate. Now I'm not sure how much we are going to have to spend in supplies in order to make a $250 profit, or how much hot chocolate made by a 5 year old sells for these days (I think it's at least $2.50 at Starbucks, but we are not Starbucks). Or how long this is going to take? I'm thinking we may be selling lemonade by the time we make $250! Any suggestions? Hurry--the big sale is this weekend!