[Dilettante_Pro]

<form method="post" action="" id="formMain"  name="formMain">
	<div id="cena">25 150</div>
	<select name="razmer_vorota" id="razmer_vorota"> 
		<option  data-price="25 150" value="2500 x 2115">2500 x 2115</option>
   		<option  data-price="30 200" value="3350 x 2390">3350 x 2390</option>
    </select>
</form>
<script>
razmer_vorota.onchange = function() {
          var i = 1;
          var timer = setInterval(function() {
                 i = i - 0.1;
                 cena.style.opacity= i;
                 if (i < 0.1) { 
                    clearInterval(timer);
                    cena.innerHTML = this.razmer_vorota[this.razmer_vorota.selectedIndex].getAttribute('data-price');
                    timer = setInterval(function() {
                       i = i + 0.1;
                       cena.style.opacity= i;
                       if (i > 1)  clearInterval(timer);
                   },100);
                }
           },100);
		
};
</script>