I had FFS over 2 years ago with Dr Zukowski in Chicago and the op cost me over 25000 US Dollars. I had a lot done and I'm very happy and impressed with his work.
As far as costs go, it all depends what you want doing. You don't have to have everything done at the same time, but if you do it means it's all over and done with in one go. I'm not sure about paying for it in installments, you'd need to speak to the Doctors office.
There are other Doctors out there doing FFS, but I chose Dr Z because of his previous work and from other folks recommending him. I suggest you do your research and choose the Doctor you feel most happiest going with and proceed from there.
Good luck