sync stock both way VirtueMart with Magento

[innovaction]

HI. Could anybody have any advice how to sync both way stock from VirtueMart and Magento ?
We run www.shopmages.com page and looking to integrate it with 3rd party providers that use VirtueMart and Magento.
Any free or commercial plugin or other solution ?

Thanks for help

Paul

[Maxim Pishnyak]

VM could use CSVI Improved (CSVfiles) and XML also. What could use Magento?