Hi,
When you add a product price with "0", HikaShop consider it as empty and act like you did not add a price.
"0" is free and if a product does not have a price, it is a free product.
And yes, you can't mix "I do sell free products" and "I don't sell free products" in the same time.
But, you can have a product with a price and a 100% discount on the product for a specific Joomla user group.
The product won't be considered as "free" but as "$0.00" due to the discount.
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.