You can build your own for almost pennies if you are somewhat electronically inclined. Heck, I'd even send you the components for whatever they cost me (very little on a single-part basis because I buy them in quantities) and what it would cost me to send them to you. I'm not doing this to make a buck. Quite the opposite. I offer them as a service to my Mopar friends and as an alternative to buying over-priced, off-the-shelf units. RTE gets like $60 before shipping last I checked. Lmk...
[FOR SALE] - Solid State Rallye Gauge Instrument Voltage Regulators (IVR)