No concrete figures have been released regarding the micro-budget film, largely (as far as I can tell) because most of the major expenses came directly out of Joss Whedon's own pocket and he simply isn't saying.
Based on this interview with Whedon, we learn that not only was he personally involved in the filming, editing, lighting and writing but that the principal actors were also on micro-salaries (e.g. either at the bottom of SAG Union Scale or just ignoring it entirely)
As well as shooting in their own house, they funded the production
themselves. "I did everything they say don't do," Whedon grins. "Great
idea to shoot next to a golf course, by the way. You know what they do
on golf courses all day? Mow." His cast consisted of regulars from his
TV shows, who gave their time "for what will ultimately be dozens of
dollars".
Since Whedon already had access to much of the equipment, it's incredibly difficult to put an actual number on the budget but based on the "bythenumbers" leak of the budget of The Village (and with the help of the IMDB Cast/Crew breakdown) we can make a few educated guesses.
- Casting - $0 - Whedon did most of this himself.
- Food Charges - $? - Whedon's wife provided a daily buffet.
- Writing - $0 - Shakespeare wrote most of the plot + dialogue, Whedon re-wrote it for production.
- Cast Salaries - $? - According to this answer, background actors in the Los Angeles area had to be paid at least $142 per 8 hour work day, and speaking parts get more.
- Music - $? (All music written and performed by Joss Whedon) - There were some players as well - Lets say $1000/day in total.
- VFX - Almost nothing. Probably less than $100K.
- Post-Production - $0 - Almost all the editing and post was apparently done by Whedon himself.
and
- 14 x days makeup = $14K
- 14 x days lighting and rigging = $100K
I'd guess that overall the film was made for substantially less than a million dollars, probably more like $500K if you discount the time that Whedon, his family and close friends put in.