I agree that the before-790 series is cheap plastic, and pretty ugly, but I had to choose between USFF 790 for 80€ (so no PCI-e gpu, and I really needed HDMI, because my TV doesn't have VGA, DVI or DP input) or SFF 780 for 40€ (on the french craiglist around me), I didn't had that much choice, and it's hidden behind my 40inch TV so you don't see the ugly duckling
And even-tho they're build like crap, they last pretty long, I have a 320 from 2005/2006, still going strong, but I don't have much use for it (except for old Windows XP games, and even tho for that there's Virtualbox)
Even tho I'm thinking about upgrading to a 990 (So I would FINALLY switch to iX CPU), or to buy a cheap 15$ 3GHz Quad Core Xeon and 2GB of RAM to upgrade to 8GB