SG59, what catalogue did you get that number from?
Those look like SG180/181. Perfect examples are offered by a dealer like Andrew G. Lajer at GBP 90 - 100.
ebay lists them between a few pounds and GBP 75 (oh well, you should not deny people their dreams).
So, probably, you are talking south of GBP 5 each, unless the cancel is special.