Hi,
You can create two manual shipping configurations.
The first one would be free, the second one would have the cost of the "hard copy of the invoice".
Thanks to the "shipping override" option, you can override the shipping address of the customer so if he choose the free one, you can empty the "shipping address".
Otherwise you would use the shipping address of the customer.
Regards,
PS : I moved the topic to the HikaShop section, because there is no relation with HikaSerial.
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.