The exam centre that my kids are taking their I/GCSEs at, shows on the fees list the following:
A Level Maths : £401
A Level Further Maths : £520
A Level Physics Exam Entry & CPAP : £1,325 OR A Level Physics Exam Entry, Tx'd to Alt Centre & CPAP : £1,559 (not sure which of these two options you'd need)
So yes you've been quoted correctly.