umm its just the fob case thats broken right?
the chip and the remote and the key are fine?? contact your local "chabi wala" he might be able to help you, as if urs broken, other peoples car keys cases might have also broken, so a spare fob case should be avalible in the market. Try your luck, i got my vitz case replaced, for Rs500
Corollas remote casing can be found at Rs.250. So try ur luck maybe ul get lucky