I've learned an interesting relation regarding salaries myself. It's not about the amount that you can live with, or what you think you need but about appreciation. I was such an idiot earlier: this whole angle was anything but clear to me.
Early in my career I never asked much and I was quite happy with what I got because I didn't spend that much. All my salaries were big enough compared to the previous salary that I didn't even think much about the fairness of it all. Given also that as a programmer I was still enjoying better than the average national salary and still better than my dad.
But eventually I realized that the only tangible way a company can truly appreciate a good employee is biting the bullet and by paying him a bigger compensation.
Even if he doesn't need it.
In the previous job I stayed for five years. Year by year I started to wonder when will they give me a raise: I still liked the job and I was considered a good programmer. I was already approaching the senior status earlier, but they reworked their career plan and bumped seniority forward into the future. Of course, seniority would have meant some standard increase in the salary. It took me those five years to determine my own value and at the end of it, I left at the brink of my five-year review that turned into an exit interview in promptu.
It wasn't about me physically needing more money: it was about me deserving being paid more money for my skills and experience, about my employer actually acknowledging their appreciation towards my contributions.
These days, I enjoy about the double of the average salary in my country. Quite a considerable increase! I still don't need all that money which has allowed me both to voluntarily work part-time and to also invest part of my earnings monthly. But now I feel like finally receiving each month the appreciation I never got in the previous job. Given my skills and experience, I'm being paid much closer to my market value now and that is what matters, eventhough I still live a small life and could easily live on my old salary.
Job markets are like any other markets: the correct price is not the cost of production plus some profit (or employee's cost of living + some more) but an arbitrary agreement between the smallest amount an employee will accept and the highest amount the employer will pay, an agreement that makes both equally happy.
The next time I'll negotiate a salary, I will have a request ready for an amount that is high enough that I won't be in a hurry to get a raise, but which is hopefully within reasonable limits depending on the job. In the case it's too high for the company, I'm willing to scale back the salary along with my monthly hours, linearly.
But my value per hour remains the same. I know my worth now.