How have you structured the pricing data in your "look up" table of products?
If you make a separate record for each combination of color, size and type, you can select a single entry from a product ID value list and it's price would be looked up.
If all variatons of size and color have the same ProductID, you can still use separate records for each one and then use a relationship such as this to look up the unit price:
LineItemsTable::ProductID = Products::ProductID AND
LineItemsTable::Size = Products::Size AND
LineItemsTable::Color = Products::Color