[рони]

SERblY,
замените строки 8 - 22 на это ...

var minCost = jQuery("input.minCost"),
    maxCost = jQuery("input.maxCost"),
    storage = sessionStorage;
jQuery("#slider").slider({
  min: 0,
  max: 1000000,
  step: 500,
  range: true,
  values: JSON.parse(storage.getItem("values")) ||[0, 1000000],
  stop: function(event, ui) {
    minCost.val(ui.values[0]);
    maxCost.val(ui.values[1]);
    storage.setItem("values", JSON.stringify(ui.values));
    },
    slide: function(event, ui){
    minCost.val(ui.values[0]);
    maxCost.val(ui.values[1]);
    }
});