As with all surgeries, advancements in technology/methods, popularity and the country you'd be having the procedure(s) performed in are three of many factors involved in the cost. FtM bottom is still considered rather 'niche'/specialised and isn't performed widely as you probably know (it's not the simplest of procedures!) so it's unlikely that it will come down in price (even in countries where surgeries are cheaper such as Thailand) until newer methods are available and there is more demand (and therefore more practice for surgeons!) to have it done.
The idiom "No pain, no gain" comes to mind; Pain management can be a complex science, but even today it's advanced enough that you won't feel much other than discomfort. As you said, it's certainly worth that to become who you want to be. :3
