The rate is usually 100RMB for individual travelers. There are also expensive one which includes banquet. The last cruise is at 22:00. You can fet to Shiliupo Ferry terminal (十六铺). The cruise will not go to Nanpu-Lupu Bridge section during the Expo. So, the route is Shiliupo - Bund - Lujiazui and then back to Shiliupu. So, it only costs a coupl of hours.