[Mr V]

In general you only need to list items that are on your robot and cost more than $1 per piece.

However there is one caveat and that is items purchased in bulk.

For example say you have a 50" of a particular size of aluminum tubing that you cut from a 8' stick of aluminum. You will need to either put the cost as that of the entire 8' stick or if you can find some place that sells it by the foot you can use the cost that they charge.

For example the place you bought that 8' stick charged you $12 but you find someone else that sells it for $1.95 per foot. You could either charge it as 6' @ $1.95 per foot, or 1 8' stick at $12 per stick.