I've worked retail in the past, spalding. My WS customers, on the whole, were no more or less well heeled than the arranger customers (if they were going for TOTL).

I think it is more economy of scale. WS's outsell arrangers (at least in the $1000+ range) probably 30 to 1 or more. This simply makes them able to sell them less expensively. And the all important content costs a LOT less per unit when you sell in those numbers. As Nedim has pointed out, the styles in an arranger are a considerable factor in it's overall cost. Only sell a few hundred, it's a sizable portion of your costs. Sell a few THOUSANDS (as WS's do) and the cost per unit goes down considerably.