Well, maybe you can do a simple session database where each visitor (member or non-members) shall be given a unique session number, which will be stored in the session table and in a certain cookie variable. Btw, by creating a cookie variable, you are able to check and update the session table. Every, item selected will be added to the items_selected table which can be identified by its session id. so, if you want to list the list of items that the buyer has selected all you have to do is to select all entries from the items_selected table where session id = session id. compute the amount.. and you'r on your way... for me its the easiest way.
