[Aetae]

<script>
function connectMaterToSlave(masterClass, slaveClass, relatedClassBeginsWith) {
  const connection = ({target, target: { classList }}) => {
    if (!classList.contains(masterClass)) return;

    for (const className of classList) {
      if (className.startsWith(relatedClassBeginsWith)) {
        document.querySelectorAll(`input.${slaveClass}.${className}`).forEach(
          input => input.value = target.value
        );
        return;
      }
    }
  };
  
  document.addEventListener('input', connection, true);
  
  return () => {
    document.removeEventListener('input', connection, true);
  }
}

connectMaterToSlave('master', 'slave', 'price_');
</script>


<input class="autosubmit master price_45s_1_fat" size="1" type="text" name="price" value="400">
<input class="autosubmit master price_45s_3_fat" size="1" type="text" name="price" value="430">
<input class="autosubmit master price_45s_20_fat" size="1" type="text" name="price" value="400">


<br/>........<br/>


<input class="autosubmit slave price_45s_1_fat" size="1" type="text" name="price" value="400">

<input class="autosubmit slave price_45s_3_fat" size="1" type="text" name="price" value="430">
<input class="autosubmit slave price_45s_20_fat" size="1" type="text" name="price" value="400">

Вот без jq.

....вот что из этого сгенерил чатгпт в jq, если надо:

function connectMasterToSlave(masterClass, slaveClass, relatedClassBeginsWith) {
    $(document).on('input', '.' + masterClass, function(event) {
        var $target = $(event.target);
      
        var classList = $target.attr('class').split(/\s+/);
        $.each(classList, function(index, className) {
            if (className.startsWith(relatedClassBeginsWith)) {
                $('input.'+ slaveClass + '.' + className).val($target.val());
            }
        });
    });
}