Yes, I've done this before with the exact same paypal form code.
What's not working?
Assuming that form is stored in a field called paypal_link:
$query = mysql_query("SELECT paypal_link FROM your_table WHERE id='$id'");
$row = mysql_fetch_array($query);
echo $row["paypal_link"];
That should echo the html which in turn will be processed by the browser.
I don't know what's working, but depending on your settings, you may need to addslashes() when inputting into db and stripslashes() when pulling out. What db field type are you using?
Cgraz