The green one is called the Red-Tailed Green Ratsnake, although it is really more or an arboreal Racer and goes by other names as well. WC imports can be purchased for $50 to $75 each but have high mortality.
Captive hatched babies, those hatched from eggs laid by gravid imports can sell for up to $300.
True captive bred and born babies go up from there.
The silver and yellow specimens posted in the other thread are generally more expensive.
The black G. janseni don't have much of a common name. I have heard Black Jansen's Ratsnake, Seleyar Ratsnake, etc.
They are a bit harder to price. When/if I produce my first generation I can't see letting them go for less than $250, if I let them go at all.
-----
Current snakes:
0.0.1 Gonyosoma oxycephala - Java locale (green)
1.2 Gonyosoma oxycephala - Jave local (green)
2.2 Gonyosoma janseni - Seleyar locale (all black)
1.2 Gonyosoma janseni - Celebes locale (Black & Tan)