you could do this using javascript on the onchange event of the select list, here is a small example:
price: $<span id="price">13</span>
<br />
<form id="form1" name="form1" method="post" action="">
Price List'
<select name="priceList" id="priceList" onChange="document.getElementById('price').innerHTML = document.form1.priceList[document.form1.priceList.selectedIndex].value">
<option value="12">Item 1 - $12</option>
<option value="13" selected="selected">Item 2 - $13</option>
<option value="14">item 3 - $14</option>
</select>
</form>