Priming tools are indeed cheap.
https://www.jegs.com/i/JEGS/555/23640/10002/-1
You can make one from an old distributor too.
However you might have fun priiming it with the motor in place. Not much room back there.
I’ve used an angle attachment like this before.
https://www.amazon.com/Ryobi-Right-D.../dp/B0781WNBF3