Get a dime bag, or at the very minimum 1 gram for a blunt. One joint should get you plenty high, I usually use .5 g's for joints and 2 g's for blunts.
Cost depends on 2 things: quality and where you live. Prices are different in different part of the world, and obviously good herb costs a bit more than crappy herb. There's no set ammount that you roll into a J or blunt,different strokes for different folks, ya know.
LOL my grandma used to say that. I remember one day I was pretty out of it and she said that and my response was, "good thing only old people get strokes."
I usually dont buy my stuff pre rolled but if youre gonna buy 2 grams of middies (more inexpensive type of pot) to roll a blunt expect to pay $10-$20 for it. One joint inhaled properly should be plenty enough to get you high.