<ul>
  <li class="item">Item 1</li>
  <li class="cost">$1.99</li>
  <li class="item">Item 2</li>
  <li class="cost">$1.99</li>
  <li class="item">Item 3</li>
  <li class="cost">$1.99</li>
</ul>

li.item:nth-child(-n+2) {
  background-color: red;
}