<script type='text/javascript'> 
$(document).ready(function(){ 
	$("#ekle").live("click",function(){
		var tutar = $("#inputum").val();
		$("#deneme").prepend('<option class="deneme_option">'+tutar+'</option>');
	});
	
}); 
</script> 

Tutar: <input type="text" id="inputum" value=""/>
<div id="ekle" style="cursor:pointer; font:11px arial; background:#eee; color:#333; display:inline;">Tutarı Ekle</div>
<br>

<select name="deneme" id="deneme">
<option class="deneme_option">500 TL</option>
<option class="deneme_option">400 TL</option>
<option class="deneme_option">120 TL</option>
<option class="deneme_option">180 TL</option>
</select>