Klara

UK sellers are all over the map on Klara — the cheapest ask at £7.05 is 35% under the median of £10.80, so there's real room to haggle if you're buying, or to undercut if you're moving stock. With nine sellers in the mix, the spread suggests either uncertainty about the card's value or different conditions in play, so it's worth shopping around rather than taking the first asking price you see.

• NotableUK asks run from £7.05 to a £10.80 median; the cheapest is 35% under the middle.