Right now you can create a new item through Zapier but you can only add the Rate for the sales order, there is no option to add the Cost for the purchase order.

Items do not have a lot of fields to begin with, it will be great if all the fields are available including custom fields, it will be just a simple mapping.

Also a new Zap should be created to Update information, not just creating items. This is very handy as items are often updated with new pricing