Those companies certainly exist in the commercial helicopter market. They buy damaged helicopters out of insurance auctions, lots of surplus parts from foreign militaries and government agencies etc. To make this work, they have the in-house IAs to inspect the parts, the network of vendors to recondition/recertify them and the logistics to pick up an unairworthy helicopter in Farawayistan. Oh, and they have the warehousing and marketing to sell and ship the parts to maintenance shops across the globe.
It's a business, as an individual who parts out a helicopter, you would be trying to compete against them in a market you know nothing about.