Ahh, you just want to make your own cheaper... doesn't always work like that (sometimes it does). There are many times when my projects cost much more than what you can buy. Not just the components but time and tools needed to complete the project.
The big companies have tons of resources tied into R&D as well as economies of scale as they mass produce product to bring down per piece pricing. Once the R&D has been paid for and the early adopters are done the pricing will come down.
Think about the 4K TV, when they first hit market they were thousands... not too long ago. Now a 55 inch is about $300-400. If the idea catches on it'll get cheaper.