Well, I ended up buying pre-made tab-top curtains to save time and effort. They were $15 a pair and I bought 20 pairs. They were the most expensive part of the entire thing. I don't recommend that route unless you intend to reuse the lodge; I splurged on materials because of the fact that we use the lodge every year for the festival and I wanted to have something that would last through subsequent generations of fest organizers. The previous lodge we'd used was made with sheets of red velveteen fabric...we forced it to last for five years, at which point we chucked the entire lodge because it was just in tatters; it really should have been burned after three. The velveteen was a bad choice of fabric too. The lodge just should not be shiny...
My original plan, though, had been to just buy yards and yards of fabric. You can find lots of places online that sell whole bolts of fabric for really cheap, or you can go to your local fabric store and have them order the bolts for you. That way you can see the fabric in person and make sure the color is right. Some fabrics are as cheap as $1.50 a yard, so that's a much better investment for you, I think. :)
And before anyone asks or jumps to conclusions...I paid for the entire lodge myself, out of my own pocket. Not with festival funds! 
~ Amanda
"Just fear me, love me, do as I say and I will be your slave..."
