You can use Security Assist to create the user registration and login functionality. The redirecting though based on a cookie will just use cookies toolkit and some hand coding.
On any of the pages you would like to restrict access to you can apply the Security Assist access rules to that page.
One your product detail page you will need to check the cookie to see if it has a particular value. If it does then you would redirect the user to another page.
If the cookie is not set to the specific value then set the cookie to this value.
If this code is in place at the top of the page it will check for the cookie, if it does not exist, like the first time the user gets to the page, then it will be created. If the user tries to go to the next items detail page or even view the same page the check of the cookie will occur and since the value has been set the user will be redirected to the page of your choice.
This is the general idea, please post back with any questions that you have about any part of this.