<div class="numerator">
    <input name="count" class="field" type="number" value="1"
      data-price="1.00" data-max="2" data-min="1"
      data-curr_rate="27.000">
      <span class="measure">кг</span>
    <button type="button" class="minus" onclick="inc(this, -1)"><span
            class="flaticon-minus-sign-of-a-line-in-horizontal-position"></span></button>
    <button type="button" class="plus" onclick="inc(this, 1)"><span
            class="flaticon-add"></span></button>
    <div class="spec" style="display:none">
        <span class="sp_p">2.00</span>
        <span class="sp_n">2</span>

        <span class="sp_p">3.00</span>
        <span class="sp_n">4</span>
    </div>
    <span class="sp_price" style="display:none">1</span>
</div>

var spec = $('.spec')
for (i = 0; i < spec.length; i++) {
var numbers = $(spec[i]).find('.sp_n');

console.log(priceList[j-1]) // данные есть
$($(numbers.parentNode).parentNode).find(".sp_price").text(priceList[j-1])
console.log($($(numbers.parentNode).parentNode).find(".sp_price").text())   // в консоле пусто