I don't know what you mean by luxury brands exactly but that whole distinction between top tier, midrange etc wasn't nearly as developed ten years ago so you can't really use that as a reference. Midrange fashion as we know it today barely existed and fashion brands were overall priced much much lower than they are today, effectively occupying a price bracket close to current midrange labels prices.
Gotcha. Not to drag this out too far, but even if most labels charged the equivalent of "midrange prices" back in the day, i still find it interesting that SS would continue to keep their prices around that level while other brands with a similar aesthetic/quality would raise their prices much higher (like what steveoffice said above)
As I wrote earlier, most other brands in SS's price bracket position themselves as "contemporary" brands-- and while that's a super nebulous term, and it's hard to define the boundary between what's "contemporary," what's "luxury," etc, for me SS occupies an interesting territory where it has all the visual elements of a much more expensive brand at two-thirds the price. And that's kinda cool. Not something I see often.