What donut did you get? Most donuts I've gotten from VooDoo were around $3 which is a reasonable price for being on theme park property. I also think VooDoo is a little bit overrated but it's definitely better than an Albertsons (or any other grocery store) donut which is more like $1 now. I think comparing it to a donut shop donut which runs $1.50-$2 is more fair.
I think I got a maple bar. Maybe I accidentally got some weird special donut they had that day but it was nothing all that great. Maybe it was just bad luck of the draw.