1- Buy the chiffon on the rolls. Yes you could probably do it cheaper to buy it not on the rolls but cutting and sewing strips and if it's something you have to hem you will go crazy by the end.
2- You won't quite use all the chiffon on your rolls so I suggest (especially when sewing your ruffle) to cut a 15 inch strip and then place with the tension on your machine until you find what will make it be a 5 inch ruffle. Not having to gather that much will really save you a lot of time. Also when you have to gather by hand your material twists more which then requires more time to untwist and sew.
3- You will notice as you sew that your chiffon curls a little on the edges. If you make sure that the curl is down it is easier to uncurl from that direction as you sew.
4- I wanted to make one of mine a bit bigger than what she suggested so I figured it would be cheaper to make the satin top longer than it would be to buy wider chiffon. So I cut it 12 inches instead of 8. It worked, but I think if I had to do it over again I would buy 6 inch instead of 5 inch chiffon and cut the satin at 10 inches. (scroll up and look at the pink and green one again and see what you think)
Total Cost: about $15 but I know totally understand when I see these for sale for $50+.
Total Time: It's hard to say. But as I said earlier this was the most time consuming project I have done yet. It is worth it in the end I promise. If I had to estimate time I would say 10 active hours. (well my first one was closer to 14hrs but I got quicker as I went so pay attention to those tips!)