[j0hnik]

<span class="item_price">Пусто</span>
  <label class="btn btn-price">
	<input type="radio" name="2145715766" id="2145715766"> Текст 1
  </label>
  <label class="btn btn-price">
	<input type="radio" name="2145715766" id="2145715766"> Текст 2
  </label>

<script>
document.querySelectorAll('input[name="2145715766"]').forEach(el=>el.onclick=e=>document.querySelector('.item_price').textContent = e.target.nextSibling.textContent);
</script>