My main business is building chassis and suspension for custom cars, but as one of very few fab shops in the area, we get appoached with all sorts of interesting (and not so interesting) projects.
Last year a few of the local demo derby guys asked us to build some engine protectors for their cars to save damage to the crank, pulleys etc. They were very pleased and brought us a new project last week. These are "universal" engine cradles for transplanting small block Chevy motors into the demo car of your choice, in this case mainly Chryslers.
The first pics show the cradle they were buying in years past, but fitup was poor and they wanted something with better fit and a bit stronger. Obviously price was also an issue but these guys usually will pay for something that works.
I designed the brackets in Solidworks and added tabs etc so it would basically be "self-fixturing" with little measuring and hard to screw up. Welding was done by my newest guy, 17 years old and currently in a welding program at the local HS. We are grooming him to start here once he graduates and he is already taking to it very well. I don't have kids so when I can train a young guy and give him something to be proud of it makes me feel good. Also doesn't hurt that he is trained my way and I don't have to unlear bad habits.
I would like to know what other guys would have charged for these, and I will share what we charged when I get some opinions. They were all built in house, from design to plasma cutting to welding.