Hi There,
We could find out the issue.
Basically, there is not issue from our side. The issue, raised for the plugins that you have used.
We have deactivated your installed extra plugins for a moment and added some domain pricing in your test domain pricing and we saw the pricing added and saved. Please check out the screenshot as reference http://prnt.sc/f0wbxo
You could also check out our example domain pricing, here http://themelooks.us/demo/ecohosting/wordpress/example/
We have added there about 160 domain entries.
In this issue, you need to deactivate your installed extra plugins one by one to find out which plugin conflict with the theme. After then, contact with the plugin support to fix the issue.
Best Regards,
ThemeLooks Support Team