<?php

$gondert=$_POST['gondert'];
if($gondert){
$fiyat=$_POST['fiyat'];

if($fiyat == 1){
$fiyat=$_POST['fiyat2'];
}

}


?>
<form method="POST">

Fiyat:
<select name="fiyat" size="1">
<option value="1" > Seçiniz</option>
<option value="100"> 100TL </option>
<option value="200"> 200TL </option>
</select>
veya
<input type="text" name="fiyat2" ><br />
<input type="submit" name="gondert" value="Kaydet">
</form>