Hello,
Well, you can consider that the store is paid directly and use the ACL system in order to just let vendors finalize an order.
Customers will just have manual payment method ("collect on delivery" which will make the order "pending") and vendors will be in special groups and could use "real" payment plugins to finalize the payment.
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.