form.html

<input type="hidden" value="100000" name="minlp" id="minlp" />
<input type="hidden" value="135000" name="maxlp" id="maxlp" />

<select id="pricesel" name="pricesel">
  <option value="0,99999">Under $100,000</option>
  <option value="100000,135000" selected="selected">$100k ~ $135k</option>
  <option value="136000,190000">$136k ~ $190k</option>
  ...
</select>

form.js

$(function() {
  if($('#pricesel').length > 0) {
    $('#pricesel').change(function() {
      var vals = $(this).val().split(',');
      $('#minlp').val(vals[0]);
      $('#maxlp').val(vals[1]);
      return false;
    });
  }
});