Primer

I just came across this again. I first saw it a couple of years back, and it had blown me away. It's especially recommended for fans of really heady science fiction.

The plot involves some garage space engineers who accidentally invent a device that transports small objects, 8 hours back in time. When they figure out how to transport humans (themselves), all hell breaks loose.

The director, Shane Caruth, reportedly made this for like 15 thousand. It was huge hit at Sundance when it was released,but, didn't see a wide distribution unfortunately.