Agree with Dave, but Genes comment re pricing is spot on. Then there is the quality aspect of their parts.
I understand (only to a particular point) that it is a balance between product-accuracy/quality/cost/margin for RS, however it seems that is is very biased to margin at on end of the scale, and same for product quality/accuracy at the other end of the scale.
In saying that, I have been very well looked after (price wise) on occasion when I have purchased from RS. But only from 1 store, and only by 1 salesperson. PS: I dont know him from a bar of soap, he simply wanted my business. And I presume he does that with all customers he serves.