They're almost all more durable than you'd think. It's usually the cushioning in a shoe that wears out when a shoe wears out so a racer, with almost no cushion, will last a very long time even though it looks flimsy as anything.
The "relatively inexpensive" thing is the kicker. Almost all of them are, in my opinion, massively overpriced for what you get. Look at the New Balance Minimus line for example. The shoes are all a thin piece of rubber with a synthetic upper. There can't be more than a couple bucks worth of material and how much R&D do you need to come up with the idea of a shoe made of a piece of flat rubber and an upper? And they're all priced in three figures. The same is true for the Mizuno Wave Universe and that new one Saucony has out.
I stocked up on the Asics Blazing Fast which was the last reasonably priced racer I could find. They're off the market now, replaced by a "new" version of the Piranha which is essentially the same shoe as the Blazing Fast but at a much higher price. My theory for the name change was that Asics wanted to jack the price up but couldn't come up with a rationale for doing it with the Blazing Fast so they decided that if they gave it a new name no one would notice that it was the same shoe but for tons more money.
I do use the Saucony Kilkenny now and again. If you can run in a cross country flat regularly I think that and the Nike Zoom Streak incarnations are all that are left for reasonably priced racing shoes.