As far as costs goes, it tends to depend on when you have your first appointment rather than when you get them fitted. In most circumstances, after turning 18 you can't get them on the NHS, but I have so again it depends.
The cut my mouth to pieces for a week, I was on painkillers everyday, but after that they haven't really bothered me. Only if I lean on my hand or something whilst I am asleep because then they obviously cut in all night and it hurts when I wake up.
For anyone who experiences anything similar, I very very strongly recommend TCP solution on the cuts. It doesn't sting cos it's in your mouth, and it stops it hurting immediately. I found that the orthodontic wax just came off.