2 bikes worth of Swiss Stop Rat yellow canti brake pads for carbon rims.
These were only used last season so a maximum of 20 hours use between them (in a season when I wasn't really going quick enough to need to slow down much !) so plenty of life left in them yet.
They retail at £40 a bike, yours for £20 a bike :-)
I'll be at the Nationals and the last 2 Notts & Derby races or can post for cost.