I don’t know what the problem is, but I can’t test with your data. One thing I can suggest is just to return some text and make sure it’s displaying in the template. Once you get that working you can try to debug the other code.
For example, replace this:
$props['prix'] = $html;
$props['prix'] = 'TESTING';
Once that’s working, you can add the other lines one by one to find the problem.