One of our friends asked John how to make a balloon arch for a party. He assembled some instructions that looked useful: http://www.youtube.com/watch?v=kJA0y1MG6OM
I hope you find one that works for you. I understand that the U.S. Government is slowly letting the National Strategic Helium Reserve be sold off to the general public, making small helium companies unable to compete, causing increased helium prices. I hope you find a good helium bottle, and I recommend Qualatex balloons, available at your local party stores.
Helium balloons can be fun, and the first video shows using a sealer on the inside of the naturally porous latex balloons. If you need it to last many days, I would recommend purchasing that stuff, too. If not, don’t worry about it.
Take some pics to share w/ us when they are made, please.