You can buy these from Subaru, yes.
Part Diagram is here
http://opposedforces.com/parts/legacy/en_b13/type_94/body_equipment_exterior/head_lamp_washer/Part#s are:
Cover assembly-lamp washer nozzle, right
86636AG250Cover assembly-lamp washer nozzle, left
86636AG260I've heard the dealer wants about $100 each for them, but excellent overseas Parts suppliers like Partsouq.com only charge Aus$32 plus postage.
The only issue is that the clip that often goes missing when the cover comes off, is apparently part of the headlight assembly. So that can't be easily replacedone unless buying a whole headlight, which is $$s.