Pictures are consistent with Rhipsalidopsis. Rhipsalidopsis are available in the US. I have 3. Here is a pic of one of them.
Note there are some minor differences, but mine is a young one and may change a bit as it gets older.
You can find different varieties here. http://mattslandscape.com/rhip...
There are many other sources.
Also wanted to say that the common name is Easter Cactus. These plants bloom in the spring.