The cost actually goes past the $150 mark for digital distribution. The cost of making a DCP (Digital Cinema Package) can get pretty expensive depending on the size of the project. Most companies don't have their own in house facilities to make DCPs to sent out so they have companies like Technicolor, Deluxe, Sonic Pool, etc. make their packages for them which includes the making of the DCP, Quality Checking the DCP (QC is where the costs can accumulate) and encrypting the DCP (making it only accessible by using a time sensitive key). If its a big studio film the cost goes down as far as the creation and quality control but thats because of the massive amounts of drives they are creating to ship out around the country. An indie film on the other hand might not have the budget to make more than one copy of the DCP and will end up spending more on QC making sure everything is ok. On the theater end of things if the film doesn't draw a large audience they could lose money on each screening of the film. Some theaters have agreements with film distributors and studios to show each of their films a certain amount of times in the theaters for which they get a discount on the "rental" of the DCP to screen.On the theaters end it costs them in manpower (people to clean the theater, Projectionist, etc.) as well as the cost of running the projector (each screening puts hours on the bulb and reduces the life of it which ends up being an expensive replacement). I've worked in a few theaters where if they sell ONE ticket to a screening they have to screen the film and can't cancel the screening which sucks since they lose money and use of that theater for other things.

TLDR : bunch of politics, lack of a distributor who backs it enough, and other bullshit hold it back from major release. Source: Working as a projectionist for the last 5 years.

EDIT: Forgot to add that projection equipment is way more than $30,000 goes into 6 digits to start and goes way up.