Personally, I doubt I'll ever buy/build another "desktop" type machine that doesn't have ECC. As others have said, the price premium of the memory itself is negligible, and the platforms are typically more reliable anyway. The main cost differential is in the CPU and motherboard, and with a surplus of used gear floating around that is plenty fast enough for me (E5 v2), that becomes a nonissue as well.
When Windows BSODs without ECC, how do you know it wasn't a memory error? Which module did it affect? I know ECC doesn't make a machine immune to BSODs, but it can assist in troubleshooting.