256GB ssd for macbook air mid 2012

The hard drive for my Macbook Air (Mid 2012) Model A1466, needs to be replaced. The Apple authorised repair centres in my region tell me that my model is obsolete and Apple does not supply the hard drive anymore.

I would like to know if it is possible to purchase a 256GB SSD for my Macbook and does it have to be of a particular specification.

Thanks