Hello,
You can have a custom field of the table "item" and that plugin to have the system calculate that:
www.hikashop.com/forum/4-how-to/85015-ne...hikashop.html#113119
And you can configure the custom field to be displayed only for some products or some categories of products.
Note that this requires the Business edition of HikaShop.
Please read the message and click on the link !
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.