Building or buying an IVR / step down voltage buck converter for the instruments

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How to build your own Solid-State Instrument Voltage Regulator (IVR) for yourself (or build them...

[FOR SALE] - Solid State Rallye Gauge Instrument Voltage Regulators (IVR)
I won't be buying an RTE...$60 USD + $55 USD shipping to Canada = $172 Cdn!