Catalogues are a general guide to prices. Catalogue Valuations in my book are based on auction results, including ebay, and on what dealers sell the notes for. Valuations tend to follow the market rather than lead it. I ignore asking prices.
Prices rise and fall depending on the volume of notes available. Ploughmans have fallen a lot in the last two years as there are a lot of new notes coming onto the market, especially common notes in medium grade, and Hibernian Bank fivers.
Auction environments can be good when several people chase an item, other times they don’t sell.
A lot of items on ebay are overgraded and over priced, especially in buy it now. Sometimes though, they are priced to sell, and do so.
Sometimes things do very well in ebay auctions. Some of the items that are frequently overpriced on ebay are £1 notes, 1951-1955. These are very common indeed, as are 10 shilling notes 1951, 1952.
There are several Ploughman notes up currently on ebay which are selling around the 180-200 Euro mark in VG-About fine grade. These notes were sold earlier this year in bulk in auction for slightly less. Also, several of the Ploughman fivers currently up on ebay were sold in auction earlier this year for much less than they are currently being offered on ebay for.
It is very much a buyers market these days, and well worth shopping around.