Hi,
first a word about why it takes so long: it's because I do actually build the prototype: no virtual realizations or vaporware.
Second, I think I can build it very cheap, without microprocessors and no need for programming/upload software and so on, it would be very cheap, less than 5$ (I think 3$ actually) , and built around standard components.
I will provide schematics and photo of the prototype.
And for a little more I can also draw the PCB, mount the components and build one to be sent to you to use as a blueprint. Please note that I have to check carefully deliver expenses ant that those expenses are not part of the bid. Also this will take time since the production of PCB takes a while.
Last but not least, in case you decide I can be fit for the work, contact me in chat: I need some details before working on the project.
Cheers,
Alex.