the prices are definitely fixed in classic mode. I still think the gen unit costs is a little high but you can easily field a nice big army with samurai inf on med funds. This is probably why the game lasts longer too as you don't have a billion ashi units running through the field, but more professional units. Your general also has rally, inspire, and stand & fight by default. The last one is a huge morale booster.

All the units also have all their abilities unlocked. Matchlocks have rapid fire, bows fire arrows, etc.