shopping cart question

The way I see it, there are three options for maintaining state in php. I've already taken the route of keeping a random session id and putting it into a database to track a user/cart. So the only variable i need to track is the session id. The three options I know of then are: 1. Putting the session id in the url 2. Putting the session id into a cookie 3. Putting the session id into a hidden input type and have every button be a form Option 3 sucks asthetically and coding wise. Option 1 is somewhat ugly because now you have a big ole session id in your url (plus I don't think search engines like these). Also, with option 1 you need to have a <?php echo "?session_id=$session_id" ?> type line in every href which is a pain in the ass. Option 2 is great, if the user uses cookies, if not, you cannot track the user at all. Anyone have the perfect solution? Thanks. Jon