This is only a personal opinion, I would never ever spend less than $50 on a PSU. Without that thing your machine doesn't work, and with a crappy one it wont work either, because you are running the risk or frying some of your components or you just wont have enough power to turn the machine on and run all of the components effectively.
This is also a personal opinion: I think that that Ultra case looks nice and has a pretty decent PSU. If it ever craps out, which I doubt that it will anytime soon, you will just have to fork out some money to get a new one. Hope this is helpful.