Dear Mike,
Yup. At the bottom of the market, you may get twice the qality for twice the money. Then there's usually a long period of diminishing returns. You might double the price again and get 50% better quality; then double it again for 10%; then double it again for 1%.
Also, what's 'better'? Even if you can't tell one picture from another, the camera you enjoy using more is still 'better'. And the camera that performs better at the limits -- low light, say -- may be 'better'. Or the lens that gives more vignetting and edge softness for some kinds of portraiture, or absolutely even illumination and corner-to-corner sharpness for some kinds of interiors or still lifes. For hand-held outdoor photography at middling apertures, of course it doesn't matter: the 'quality plateau' is so low it can be met by an Exa with a Ludwig Meritar. But I'd still be happier using a Leica. And it would be more versatile.
Cheers,
R.