It's not simple math as buying Timaatar.
Rafale costs $85 million, for 36 rafales around $3 billion
Weapons package $25 million, so it's a hundred M short of $1 billion.
The life cycle of rafale is 40 years, LCC for 10 years is close to $2 billion. $53 million/jet
Setting up of two maintenance depot incl training of staff costs another $1 billion.
$1.7 billion for modifications, additional packages, or India specific changes, and for ToT this part is mostly classified.
Also, 50% of it is offset and is invested back in India.