well

all good 20 inch tires ( high pressure, compound and such ) are as expensive to make as full size high performance tires.... BUT usually the demand is very much smaller......

I started selling Schwalbe tires and specialize on 20 inch ( and 16 ) but again the demand is somewhat limited. No 50 % off here any time soon ... :-)

Sometimes people are just facisnated that they even can find them.... like mango colored stelvios ... or the new 1.5 racers ( which will be in stock in 2 weeks ) ... no need to discount them ...

Thor