That is true, if you can handle a ton of classes, that seems to be the business model. I personally found 3-4 classes a semester to be a huge load to handle and I was only working part time. Maybe you are smarter and more hard working than me, but I couldn't imagine doing 5-6 classes and a full time job, if that is your case. That course load is much better suited to a full time student. But if you did that, it is true, your degree could end up being as cheap as like $20k
Considering the rankings:
Minot State ranked 106 in the midwest
WGU is unranked... which isn't a good sign
What it comes down to, as I said, WGU is far from the worst you could do. But WGU is known as an "online school," something that a lot of employers shy away from or instantly disregard.
All that I am saying is that there is a reason WGU is so cheap, some good reasons, some bad. Since it's a non-profit, it is much cheaper, since they aren't inflating prices to make money. But it also has lots of low paid professors and a low demand due to it's low ranking and not great reputation both academically and in the workforce.
Personally, I would much rather be telling people and employers for the next year that I went to "generic state school" and have them picture an actual building that is good enough to be worthy of some of our tax dollars instead of "oh, one of those online schools." I think that's worth 10 or 20k extra. It sounds like you are decided on WGU.