While I can't say I'm going send them $500, I think Relonch is an interesting concept.
What's Relonch? Basically, an iPhone case with an APS-C sensor, battery, and f/2.0 lens.
It is little more than a fleshed out idea and prototype at this point, but I could see maybe buying one if it lives up to the preproduction hype. Here's a very short video showing the gist of Relonch:
I don't see it as a complete replacement for my DSLR, but I really love that it adds a big APS-C sensor to the iPhone. Honestly, I feel like this is a better way to make a smartphone-based camera than the ILCs running Android, because it literally uses your smartphone. It's not a separate device; everything is setup exactly the way it always is.
It's a long road to production and I do have some issues with their concept, but overall I think this will make an interesting product, which could potentially wind up in my bag. Well, unless I don't buy a new iPhone.
For more info or to give them money: https://relonch.com/