Often money can feel uncomfortable to talk about. Cost is a big part of therapy, it can feel that therapy is expensive and unaffordable. However, it is an investment, think of it like the gym, your trying to improve your health. People spend all the time for the physical health, but when it comes to mental health people are more reluctant. It's important to remember as well that you are paying for a professional, not a friend that is supportive, but usually someone with a qualification and a wealth of knowledge and experience who is focused on helping you. Studies do show that spending your money on therapy is worthwhile, with helping you to deal with your challenges and improving quality of life.
As a therapist I am aware of these costs, so I try to offer concessions where I can, and I offer later slots, and online to help reduce other loss of money like covering transport. At the end of the day there is no substitute for getting help, and the mental health industry is one that requires a lot of training.
But all of that is about why you should pay. What should you pay? For me the answer is as little as you need to. Ask if the therapist you chose might be able to offer you a reduced rate. Have a look around and see if there are any free options if you really can't afford it, be aware that waiting times will probably be quite a while, especially compared to private. Another option may be to see if there is any funding available e.g., from your place of work. If there is really no way that you can wait and you have no money then there are some online resources and crisis lines which may be of use;
Samaritans: 116 123
Therapy can give you benefits that last for months or even years, in some cases lifetimes. So it is a long game, to change the way you think doesn't happen overnight but once you have those skills then they are yours. More importantly you could be in a place where you can build additional skills without a professional's help.