Out of pocket costs? I don't really know - I'd guess less than $1000, probably mostly food, props, costumes, etc. The second one probably cost more than the first just due to the amount of destruction, makeup/blood fx, etc.
And of course probably 5-10,000 hours of practice at martial arts, stunts, filmmaking, etc... multiplied by all the key people involved.
That's what I'm getting at - the out of pocket costs aren't what's important with these, and if you focus on those you won't be able to compete. The important part is the time they've put in that enables them to do what they do. If you don't have that, then you'll end up spending a lot more because you'll have to hire people that do - or else you're going to end up with a significantly inferior production.
So the question isn't really "what did those shorts cost?", it's "what would it cost you to do the same thing?". So figure a stunt coordinator/choreographer at probably $1000/day or more, plus 3-4 stunt people/actors at say $750/day (I'm just making these numbers up - but if anything I'm probably on the low side). You'll also need a camera and sound person at minimum, plus someone for grip/lighting and a PA/general assistant. Probably going to end up between $5-8k/day total. You'll probably need a day or two of choreography and rehearsal, plus 3-4 shooting days... so you're looking at a $25-30k range.
Now maybe if you've got an amazing, mind-blowing script and some realistic prospects for huge exposure you could convince everyone to work for less and get the budget down to the $10k range, but probably not much less. These people are all actively working on their own projects, any time they spend on yours is taking time away from those - so you'll need some incentive to convince them to work on yours instead, and part of that incentive is probably going to have to be money.
So clearly it's not going to be cost effective to do something like that, unless you've got significant sales/revenue lined up for the project ahead of time. It's certainly not going to work with youtube ad revenues alone.
That's going to be the challenge with projects like this - you're competing with people who can do it far far cheaper than you can because they've been dedicating their life to it for years. If you haven't done that, the options are to hire people who have, or get started on a 10-year plan to get there yourself.
You also said their last feature cost $100K, and they may have made it back through foreign sales. Can you tell me more?
I don't know a lot of the details. I know they spent about $50-60k on the production, which was primarily money they'd earned/saved over about 6 years. For post they raised about $10k via crowdfunding (which I contributed to), I think they might have picked up some small private investments as well. At the premier they said their total budget was close to $100k - I'm not sure if that was all out of pocket or included some deferments as well.
Once the film was done they got a sales agent who sold distribution rights to a variety of international territories. I don't know what kind of deals they're getting on those, but based on what I've heard from other people selling internationally it's probably $5-10k per territory. They have a small US distributor, they sell on their own site, and they have a booth at comic-con each year where they sell their DVDs and t-shirts, posters, etc. I don't think they've made a lot of money with it, but after a couple of years I'd guess they've at least roughly broken even between direct sales and foreign rights.
It's certainly not a way to get rich, but it enables them to keep doing what they want to be doing - and it's clearly part of a long term plan. They're not just looking to make a big breakout hit that launches them into hollywood - they're building a brand, an audience, a catalog of projects, etc - all in pursuit of making the best action/martial arts films possible, the kind they aren't seeing being made in hollywood. And that's the key - they're willing to put in the time and effort because it's their passion, and if you're approaching it from a purely business standpoint the approach they're taking probably won't make much sense, or be particularly relevant.
