The cost is similar in most driving schools, & you will be able to pay in stages. I paid approx 900€ for my daughter recently, with 2 attempts at the code & 2 attempts at the actual test (method traditionelle)
Once you hand over the required documents they take care of all the paper work which is a relief ! in my case the ecole took her to take her code & actual driving test, I did absolutely nothing except pay ! I wd suggest you ask at a couple of schools for a quote before you start to be sure.
You didn't say what age she is, There are 2 methods, one called "conduite accompagné" where they can drive from 16 yrs old, but take the test at 18 yrs old, they clock up hours with you after an initial few lessons with instructor. the advantage is the insurance is cheaper once they are finally out on their own
The other method is when they just drive with an instructor. min. 20 hours.(traditionelle) its faster to pass this way, but they have less actual practical experience. clearly if you have no time, no car, (or no wish for conflict) this is the method !
Hope this helps, just one other thing, once they pass the "code" they have 6 months to pass the test, if not they have to do the code again!