I don't know if you can call this a "great" bargain but its definitely nicely priced, the lowest I've seen it here. If you looking for plain socks you might just find it useful to know they are selling 3 pairs of nike socks (white) for $9.95 instead of the usual $19.95, this is not a promotion of any kind I think, maybe just a new price or whatever. Actually in hindsight it might've been a price tag error. I can't say if this is nation wide or not either, the ones I got were from the sydney city centre store, so your mileage may vary.
OP, are the black ones on sale too by any chance? Or just the white?