i dunno, i think war darts would be pretty effective in the mid game and then throwing spears after that ..
the armour drz is using atm is reasonably cost effective, but it's ~~ 450 gold (pre discount) for the armours
i'd say at that point it's reasonable to spend ~~ 171 (pre discount) on throwing axes or perhaps 256 (pre disc.) on javelins, provided they get the job done
not to mention the ridiculous effectiveness of having 10+ shield throwers defending a castle