BountySource (https://www.bountysource.com/) tries to monetize bug fixes and light work. This is probably closer to the Bugzilla side of the proposed solution.
IMHO the core problem, dependencies, is not addressed in the solution. "A lot of mid-size companies would like to be able to pay for support for the software they're using, but can't find anyone to provide it." makes a whole lot of sense for people developing products that are directly consumed by companies, but that funding rarely if ever reaches the developers of the dependencies. So you end up with a situation where people developing interfaces for technologies (and not those developing the core technologies) receiving the lion share of donations in the open source space.
If you think about open source development as "basic research", the current state of affairs makes perfect sense and the "funding model" is well-established: government grants or private grants (e.g. GSOC or hiring the developers).
There is also https://gratipay.com/ where you can donate a set amount every month instead of paying bug bounties.
I feel like there is a lot more glue code (that is, interfaces connecting core technologies) than there is code making up the core technologies themselves. From this it follows logically that the developers of the former ought to receive the lion's share of funding because they do the lion's share of the work.
IMHO the core problem, dependencies, is not addressed in the solution. "A lot of mid-size companies would like to be able to pay for support for the software they're using, but can't find anyone to provide it." makes a whole lot of sense for people developing products that are directly consumed by companies, but that funding rarely if ever reaches the developers of the dependencies. So you end up with a situation where people developing interfaces for technologies (and not those developing the core technologies) receiving the lion share of donations in the open source space.
If you think about open source development as "basic research", the current state of affairs makes perfect sense and the "funding model" is well-established: government grants or private grants (e.g. GSOC or hiring the developers).