First you say the factory ECU is fine and shops can reprogram it. I called a couple, they do not reprogram it. They alter the tables and tweak the settings.From his posts I can only assume his level of knowledge is not current. Everything he has posted about ECUs is wrong. Demonstrably so.
I get that I'm the new guy, and I will heed advice from others.. but not blindly so.
Engine ECUs are not magical boxes of unicorn tears. Its a low powered PIC with some IO circuits and lookup tables. Factory ECUs can be programmed for standalone mode. Programming services are easy to find. If not, for $400 you can get a standalone, programmable ECU.
Now you state a programmable ECU are available for $400 bucks. Those same shops said, no, they will not take an empty ECU and develop the program.
Last point, I have developed real time building control systems; with some of the work in assembly some in higher level languages. The cost is not cheap, and this is a low volume business.