How are you taking orders and accepting payments?
Basically, I'd suggest you use a shopping cart which will allow you to add these options right in the software. The big three FREE options for shopping carts are osCommerce, Cube Cart (v3), and Zen-Cart.
Personally, I like Zen-Cart, but it's not really for beginners or the faint of heart. Cube Cart is popular here, but I find it lacking in some basic features like a contact us form. And for a lot of add-ons to Cube Cart you should be prepared to pay.
osCommerce is pretty complex, too, but probably has the most add-ons of any shopping cart.
Then again, if you don't need them, don't worry about who has the most add-ons. Any one of those three will provide this particular feature.
You can use PayPal with any of them, too, if you don't have your own credit card processor and secure site. I use PayPal for payments.
In a shopping cart software, you would create your base product and price, then create what are known as attributes. Those would be your different feature and pricing options. You then add your attributes to your product, and everything will show up on your online catalog product page.
Like I said, Zen-Cart needs experience, Cube Cart is easier, and I'm not sure how osCommerce is for templating.
If you just want to build your own pages you could do it with forms, php, and PayPal payment buttons, along with a little bit of forms validation, but again, that would take some experience.
Good luck!
How do I set up these options for my site? 
