The big variable in trying to guess an indie movie's budget just from watching it is that a con man producer can get huge amounts of work done for free by wannabes: people just trying to get IMDB credits or samples of work for their reels, or people with no professional aspirations, but who want the "glamour" and bragging value of telling everyone they're "making a movie." Producers often con people into working free by promising a piece of "the back end."
Gunter was throwing around the $800,000 figure at the Los Angeles Film Market, but was willing to sell for $80,000. Watch the long trailer: these aren't professional actors with SAG cards, they're friends and family and maybe some local amateurs. Gunter could have easily done his own music, conned some aspiring editor and camera people to work years on end. It's really hard to know, but the scale and logistics make me guess at minimum tens of thousands. Could be much more if he actually paid people, or much less if he's a cleverer con man than I think he is.
The other question is whether he got investors. A common con is to raise a much more money than you spend on the movie, then pocket the difference. Are there dentists where Gunter lives who would love to be dentist/producers? Pretty likely. A friend doing a $150,000 horror film got $50,000 of that from a nerdy computer hundred-thousandaire who never read the script and had only one question: would there be a premiere where he could bring a date to walk "the red carpet?"
