Ian Steadman has done some work on this, you might take a look at this.
You definately want a 5v power supply. they say it needs 2 amps but i think steady found it didnt need anywhere near 2 amps.
https://ianstedman.wordpress.com/gbs-82xx-experiments/
I only recently bought one of these boards myself and have only had the time to also get a power supply so far but with Christmas time coming up I should hopefully get a chance to go over the nice link you supplied.
I also got a 5V 2A supply, mainly due to the fact the manual said that's what it required. If it only ends up pulling 500mA the oh well I guess.
I also have a few other older machines besides Amigas which will also potentially use the GBS 8200.
