Hello. . . maybe try a locksmith? (self serving, I know)
We charge about $3 for a non-sidewinder, non transponder Subaru key. $5 if you want one with a plastic head.
Dealer should charge less than $20 even if they sell you the OEM blank, which I'm willing to bet you a Starbucks house brew they also keep Curtis (or some other aftermarket) blanks that usually go for less than a ten-spot even if they hate you. When I worked at Subaru in the late 90's I think we charged $2 per key.
Wal-mart and most hardware stores usually suck at cutting keys. . but the margins are good enough that even if they have to remake 3 of 4 they're still turning a profit.
Any locksmith worth his brass scrap should be able to decode and recut a key to factory spec. . .better still if you have a keycode, which most dealers will give you for the asking, no charge. You will have to ask in person, with proof of ownership and positive ID at the parts counter, however.