First of all thank you very much for using the wp travel plugin.
Now coming to your query, the theme by default does not show the price along with the comma.
But we have provided the custom code that adds a separator in the price in the single trip page and we assume you add that code.
Actually the code we provided works where the filter “wp_travel_itinerary_price” is used, In case of total price, the filter is not used so the price is not displayed with the comma where total price is displayed even with the addition of that custom code.
However, we will consider it as the requested feature and try to include them in the coming updates if possible.
Also, if you require then you can always consider hiring the developer.
To hire a developer please refer to below given link: