Each products can have as many options you wish to add. For each option you can add as many attribute you wish and can be set to have a price that will be added to the product original price if selected. That will allow you to set your product and prices exactly the way you want it. (If you posting a T-Shirt, you can add Size option, Color Option, Etc.. and lets say for size xxl you adding $2.50 on the original price)
