sovsem-nub,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
<select class="selectDost" >
<option value="dost">Доставка 300 руб. </option>
<option value="dostDrTK">Другая ТК </option>
<option value="dostPEK">Доставка ТК "ПЭК" </option>
<option value="sam" selected="selected">Самовывоз 0 руб. </option>
</select>
<script>
var sel = document.querySelector('.selectDost');
function getPrice()
{
return {dost : 300, dostDrTK : 200, dostPEK : 100, sam : 0}[sel.value]
}
</script>
<a href="#" onclick="alert(getPrice()); return false;">price!</a>
</body>
</html>