Oh man here I come to plug my favorite low budget or indy-ish sci-fi movies!

First, Coherence (2013). This movie was quite low budget but doesn't feel like it because the story is so engaging. The hours I spent reading about this movie, reviewing timelines, etc after I watched it... It's a great film and the discussions and theories about it are exactly the type of rabbit hole I love.

Resolution (2012) has a unique and interesting concept, but I mention it mostly because it is low budget and related to The Endless (2018) which is pushing the definition of low budget but is phenomenal. The story lines overlap and Resolution came out first, but I watched The Endless before I'd ever heard of Resolution and I think I prefer that watch order, honestly. Both are great films though and worth the watch if you're interested in cosmic horror/sci-fi type stories.