How many grams of Saffron for Rice? A common way of buying saffron in Sweden is to buy it pre-ground in bags of 0.5 grams.

Most saffron rice recipes use "threads" or "strands" which is pretty much useless for me.

What's a good saffron/rice ratio, in grams/deciliter?
A quick search does not really give a good answer to your question

For example, one recipe calls for 2 pinch of saffron for 2 cups of (dry) rice; another 3/4 tea spoon of crumble saffron for 3 cups of rice.

Have a looksie at this wikihow page.

In any case, I would highly suggest you try to find either Spanish or Iranian saffron, and if possible not pre-grounded. 

And skip whatever cheap substitute you will find.