Nukes are also WWII era technology, yet you would face some very critical questions if you tried to build one in your back yard. So are rocket engines and jet engines for that matter.
This type of jig grinder is absolutely not comparable to the things you can find on Ebay, let alone for 5k.
Also, if they were model rocketry or ham radio enthusiasts who took things way, way, way too far they're still in trouble for all the oil smuggling and money laundering they did.
This type of jig grinder is absolutely not comparable to the things you can find on Ebay, let alone for 5k.