I have stocks of by far the most popular model the 2025 series Airguides. These speedos read up to 50mph/80kph and are available in black or white and mph or kph.
KPH units are AUD$150ea plus $15 delivery each (discounts for OEM quantities)
MPH units are USD$150ea plus $15 airmail delivery each (discounts for OEM quantities)
Parts are currently available. Stocks are limited and these gauges are not manufactured anymore.
I can't do custom speeds as the Airguide assembly is genuine and can't be modified.
I do not have older types for classic boats or information about who may. Since the older types went out of production 20+ years ago, you would need to consider upgrading to the 2025 series while you can still get those from here or finding a way to refurbish and restore your old unit. I'm sorry I can't help at all with that.
Please email me with details of what you are looking for using the contact page or speedos@airguide.com.au