As was explained by RolloZ170 (I had a very long enlightening discussion over pm with him) - Gigabyte LGA 4677 MBs do not restrict use of D0 stepping (like my supermicro does unfortunately)
earlier stepping ES CPUs are a very much gamble and very unlikely to work even on Gigabyte despite their liberal openness,
that's why QYF... are recommended from first ES/QS wave (since those are more towards QS spectrum, therefore aren't designed only for hardware but also for software compatibility developments) QV../QW../QX.. (not sure about Q1..) on a design range more towards pure ES samples with stepping (and functionality) not implemented on most retail boards (unless you're BIOS modding wizard).
As for availability of "cheap" versions - depends on your definition of "cheap", most prod versions are still being sold by 50% higher over Intel's "recommended" price.
There are plenty of cheap D0 stepping CPUs (as many users/sellers reporting - supported by Gigabyte boards), for instance ebay China-located items: 204381467422, 125995652712, 364324430741 (I've never bought from them, nor affiliated in any way) in $200-$250 range, while item 175826589225 from US is advertised as having E3 stepping (more retail grade) and theoretically (if it's really E3) should work on more boards (but it's more expensive - starting from $800+delivery, another question is about seller' reliability because of too few sales made and lack of feedback as seller).
Prod/retail CPUs have stepping E5 or S3.
There are production low-core Bronze CPUs available starting from around $600 and up, but Silver/Gold goes for $800~$1500.
Still waiting for market availability myself keeping an eye until something suitable starts being thrown into market hopefully at around $500 but above Dn stepping (again - compatibility with SuperMicro).
P.S. ohh, and of course reminder - ES/QS CPUs aren't designed for long-term life or stability, therefore it's on your own risk.