I am wondering. Is there way to include inventory levels with each product option in CartThrob Pro?
e.g. 10 Smalls, 5 Mediums, 2 Larges.
Yes, as long as you only need to track inventory on one set of product options.
Map 'Product Inventory Field Name' to your product options field in the Cartthrob/Products settings page.
The default Cartthrob fieldtype needs no additional configuration.
If you are using a Matrix field, make sure you have an {inventory}
column.
If you need to track inventory over multiple product option groups, take a look at their Price Modifiers Configurator Fieldtype.