For stuff like steel tubing and random shapes, the crane just tosses a couple of tons over the wall to re-stock with. Oh yea, the expert isn't supposed to tell the team what you will be able to find, and what you must make. In addition, the next day, before the crane comes and puts your machine onto the truck, you and the health and safety inspectors go over the machine, and add things like belt guards to make them happy. Since its at the test site, the supply of parts, and tools are very limited. You get your expenses paid, and a small appearance fee.
Finalists get medals, the overall winner gets one years custody of the scrap trophy.
Of much greater personal value is the hunk of your creation, that you sawed off at the end of the test day to hang on your office wall, and years of great bragging about what you built. The TV company paid for the plane tickets, the hotel, and meals. Any extra days after the show was taped, and plane fare for non-participants was the team members responsibility. Well I used vacation time. For US contestants, you should figure on a full week per show.