I think it is really hard to pull off a genre piece like this on a limited budget because the props, locations, acting, direction and editing quickly reveal it for what it truly is.
Okay, I wanna make a film about the end of the world. I have no budget. The last thing I'm going to try and do is recreate the visual intensity of a disaster epic. Imagine trying to pull off the kinds of shots from of Lars Von Triers' Meloncholia without access to the resources necessary. So, what do I do? I look at what I've got around me, and assess the resources I do have. After doing this either I realise I can't make my end of the world epic, or that I have to make one that doesn't rely on these genre forms. I can maybe do it with story and character, but not with CGI and grand sets.
I think the same kind of rationale needs to be applied to these kind of pieces. Unless you do, I believe the films created will fall well short of what you could potentially create.
But hey, you might completely disagree