Different prices for different options

Currently we have to set up different items for each price. For instance, we have child tights, adult tights, and plus size tights because they are each a different price. Some of our plus size sweatshirts change price for each 2X, 3X, and 4X, but we don't really want to set up different items for each size. It would be very helpful if we could setup one item with pricing based on the options selected and inventory based on the options available which would also prevent them from ordering if there is no inventory for that option.