Hi,
HikaMarket does not provide features of HikaShop commercial packages, it adds new features for the front-end edition and the multi-vendor.
I don't know if it was me or maybe Nicolas who told you that the free version of HikaShop was enough, but we shouldn't have the detail that you required the custom field for... product, order, or I don't know.
Please check the comparison page for some explanations on the custom fields :
www.hikashop.com/extensions.html
The "product custom field" are included in HikaShop essential (and also the Business one) ; when the order and item custom fields are in the Business.
Depending the types of custom field you required, it will influence the HikaShop edition.
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.