Take a drip tip, I have a machine that will spit one out every 20 seconds or so. But there is at least $.50 worth of stainless steel involved, plus tooling, electricity, and other expenses involved. I thought about building a rba, but decided not to. Most retailers mark up a item by 100 to 300 %. I could make a profit selling them for $30 - $40 each but by the time retailers were done marking them up it would be closer to the $100 mark.