If you're just looking for something to sync the carbs you can make one pretty easy. I made mine for about $10 in parts over 15 years ago and have been using it for bikes/sleds for that long. It's just as accurate as my Carbtune 2.
As long as your carbs have a port to attach a vacuum line to it's easy to make one.
Here's an example right here:
$1.55 Carb Sync Tool by Marty Ignazito
If you have four separate TB's, just make two units of the exact same dimensions.
And they work just as good as the expensive units.