The phrase "it is available in" is correct and usable in written English. You can use it when you are referring to something that can be found or obtained in a particular place or from a particular source. For example, "This new model of phone is available in stores across the country.".
It is available in California, not nationally.
It is available in stores for $249.
Now, it is available in the United States.
It is available in dozens of colors and fabrics.
It is available in maple (shown) or cherry veneer.
It is available in hardback, paperback and on audio-tape.
None of it is available in-store.
Thanks to Ludwig my first paper got accepted! The editor wrote me that my manuscript was well-written
Listya Utami K.
PhD Student in Biology, Bandung Institute of Technology, Indonesia