I have neither a vested interest nor a chauvenistic rationale, but have to agree with Epex KH. Iranian saffron is considered to be the best, and is the standard against which others are compared.
With saffron, quality is judged by color (there should be few yellow threads, and the others should be a deep, rich red), aroma, and flavor. There actually are international standards, expressed in a numeric scale, for these factors, and Iranian always scores highest. For instance, the minimum color standard for ISO Category 1 saffron (the highest quality) is 190. The last ounce of Iranian I bought came in at 240, and I've seen it as high as 256.
Doesn't mean you can't get burned with Iranian. As with everything else, there are unscrupulous purveyors who will dilute and adultrate products. But if you buy from reliable suppliers Iranian is well worth the price. Let's face it, if you're paying that much for a spice, you may as well go with the best, even if it carries a premium price.
The Spanish national standards echo the ISO's, btw. But not all national standards do. So even if the saffron you buy is labeled with a breakdown be sure you know which standards are being used. If it doesn't provide a standards breakdown---or at least identify the category---maybe you should question it.
Edited by KYHeirloomer - 5/1/11 at 7:10pm
I also agree with Epex Kh, I've done some search and found this website where you can get Iranian saffron @ a good price:
Initial cost is high but really, truly how much does it impact cost-per-plate basis? A pinch of saffron thread weighs next-to-nothing and goes a long way. 28 grams, many servings per gram...you can easily recoup that cost by a very small price increase that nobody would notice.