i have a 20 year old st magdalenes single malt and was wondering what its worth all i know from the labelling and enclosed letter was that it was a limited edition of 396 bottles produced to commemorate 100 years of engineering at United Distillers and Vintners @ Waterloo Street in Glasgow in 1998/99. my other friend who has a bottle says it is known as St Magdalenes Waterloo Street, i was just wondering the value and best way to sell if worth it.thanks in advance