I've been a runner for years, and as someone who also likes to get a deal, I've been buying discount running shoes for just as many years. I was recently convinced to try out Super Jock n' Jill, however, and I don't think I'll ever go back to discount shoes.
A trainer recently told me that the material in running shoes slowly degrades, so that even if you don't use them, they aren't nearly as effective after about 8 months. So buying from those discount stores, where shoes have been sitting in a warehouse (or other stores) for months, sort of defeats the point.
At Super Jock n' Jill, the salespeople always take your foot size and shape, your arch style, AND your running style into consideration before selling you a shoe. And they aren't selling you just what is most expensive. Most of thier shoes are around $90, so they are in it to sell you whatever shoe works best. I feel so confident now knowing that not only are my shoes fitted for comfort and performance, but to prevent injury.
Downfalls: not as cheap as the discount competitors, and not a huge amount of locations. Upswings: personal attention, quality merchandise, and discounts for trainiers and coaches.