[ebbi]

> I'd have to fill up my backpack with the heavy camera equipment and carry it around everywhere, which would make photography more labourious and less spontaneous.

I'd recommend looking into a camera such as a Ricoh GR series. Yes, it is an additional cost, so it doesn't solve the 'expense' part of the equation, but you'd get significantly better photos from it than any phone camera, plus it's very compact so wouldn't need to lug around much at all in terms of equipment.

Or something like a Fujifilm XM5 with a pancake lens - this will give you a compact setup, with the flexibility of using different lenses if you wished.