You can still purchase new copies of Moriyama In Color: Now and Never Again at reasonable prices. Ditto the recent Tokyo (which also appears to be color - I only saw the cover). Of all places, Target sells these online.
Others also available at reasonable prices include Moriyama-Shinjuki-Araki. And if you want the trademark gritty black and white Moriyama images, you want Tales of Tono: Small book, some photos appear to have been photocopied for an extra-contrasty look. Most importantly, it contains an essay by Moriyama himself.