PPRuNe Pop - I used Spinks to auction a medal for me, it was posthumously awarded to my great uncle for the defence of Mafeking, it was valued at GBP300 to GBP400 but a couple of people wanted it badly enough and it sold at GBP1250.00, so catalogue values are only a guide.
The defence of Mafeking medal is much more rare than the relief of Mafeking medal as there were not so many awarded.