I need a landscape telephoto

I'm currently saving up for a telephoto lense that will be used primarily for landscapes. I've been looking hard at the 70-200 f/4L. I like the price and optical quaility, but i wonder can I find better optical quality without breaking the bank? The 70-200 f/4 IS reportedly has better optical quality but it also costs $1,150...about twice the price of the non IS.

This lense will be mounted on a tripod most of the time and I don't really need IS, but I want that image quality improvement that the f/4 IS provides over the older non IS f/4. Is there a non IS lense out there that would provide optics equal to the f/4 IS but at a lower price point?

Should I go third party or just stick with the $600 Canon lens?

Thanks in advance,

Karl