When my mother started work (1950) she had two wool twinsets and skirts bought for her as the core of her working wardrobe. That's it.
Actually, I'm looking at this list thinking 'hmm, got a few gaps in my 1942 wardrobe to fill' :D
Anyone read Geneveieve Antoine Dariaux's 'A Guide to Elegance'? I recommend it. About 15-20 years further along, but still adhering to very strict wardrobe rules. Her 'Ideal Wardrobe' entry actually itemizes clothing by the <i>hour</i> in each day:
WINTER, 6 pm: 'A black wool dress, not very decollete. This is the triumph of the haute couture and the uniform of city dwellers. It will take you everywhere from the bistro to the theatre, stopping en route for all the informal dinner parties on your social calendar'
WINTER, 7 pm: 'A black crepe dress, this one quite decollete, for more formal dinners and more elegant restaurants'
Oh, and re: the cost. I guess we have to remember that women on an average or lower income would still make all their clothes as a matter of course until the late 50s at the earliest. At least, that's how it went in the UK.