It's not too hard, but does take a little more thought.
You can use any bottle, tupperware etc. Here's the procedure. (Or just fill the little plastic or paper bags at the store and tag them. Bring it home and refill your containers there...)
Bring your container to the front desk (place like Whole Foods) and ask them to weigh it empty. Use a Sharpie or sticker and put that number on the top of the container. Then fill with what you want (herbs, couscous etc ) put the number of the item on the sticker or label and bring it when you check out.
At co-ops like Mississippi Market, Wedge etc. there are often scales for you to pre-weigh the container yourself. I think you also post-weigh and label it. I've messed up before and they've always been really great about it. (Forgotten to label, or pre-weigh once...)
Items I buy in bulk with major savings...
whole wheat couscous (I don't care much for whole wheat pasta, but this is good)
I keep meaning to do pastas and more, but this is what I've managed so far. Do any of you have bulk favs?