Justaucorps aren't nearly as useful though imo, but overall I think there are about as many class specific robes as there are robes either class can use. The thing is the Red, White and Black robes are all essentially the same robes with different alignment usages and other small variations-the auto 1 robes sorces get are each unique in function and something that both classes would benefit from, and sorces get some sorc spell slot robes that are pretty much the same as the ones wizards get anyway.
Let's see, wizards get
White Robes of the Solinari
Red Robes of the Lunitari
Black Robes of the Nuitari
(I probably mispelled and mixed some of those up but you get it)
Justaucorps
Red Wizard Robes (or something like that)
Sorcerers get
Lesser Robes of Wonderous Weaving
Robes of Wonderous Weaving
Sorcerers Robes
Robes of Muted Action
Robes of Transcendental Thought
Robes of ....something something, one of the auto 1 robes
Then there are all the robes that either of them can use
I might have left out some or mixed some up but that's as best I could do from memory