Sounds like a fun class. Wool is beautiful to work with and I think it will be a worthwhile investment for this class. As the others have mentioned, you can buy thrift shop articles, deconstruct, felt and even dye to save some money. Check out etsy, often you can get quite good bargains if you contact the sellers and explain what you need. I am currently dry felting a baby blanket of my own design. Etsy has been very useful and I have made contact with a wonderful supplier of wool tops who hand dyes. She even threw in a couple of bags free, which was most kind. Pure wool felt is a dream to work with and behaves very differently to cheaper synthetic felt. I think you will love the class and maybe afterwards you can sell some of the resulting pieces to finance the purchases. Scrap bags are a great idea, so don't discount that either.

Quilting Arts had a segment this morning on dying wool and felted wool. It was pretty interesting.