The first version of Blood Bowl cost 50 euros when it was first released in 2009 - with eight races. The other releases each cost more than Dungeonbowl (and added new races). Compared to that, this DLC way of pricing seems pretty cheap to me.
Also, if I'll be playing Dungeonbowl as much as I've played Blood Bowl (hundreds of hours over many years) I really don't have the heart to complain about prices. Cents per hour is almost free entertainment. It's hard to find cheaper pastimes (not counting the price of a PC and Internet)