I can't believe what a judgemental lot you all (or so many of you) are.
Surrogacy is not buying/selling a baby or renting a womb. In the U.K. you can only pay reasonable expenses to a surrogate.
It is ignorant and patronising beyond all measure to assume surrogates are poor people doing it for the money and that all people who resort to surrogacy are rich people seeking to exploit someone less fortunate. The majority of surrogates do it out of genuine altruism. How could this not be the case when they are only paid expenses.
Many people are unable to have children the traditional way be it because of infertility, age, risk to health of being pregnant or a same sex relationship. If medicine allows it and there are people kind enough to offer their bodies to make it happen, what right do others have to judge those decisions.
Fostering and adoption is not the same for a multitude of reasons and I don't think anyone could honestly say that either options compare, apart from perhaps the adoption of a baby.
Similarly, there is nothing wrong or strange about wanting a child that is genetically your own. That is precisely what every living create on Earth has evolved to strive to achieve.
And why shouldn't a woman of 50 have a child. Men are able to have children 30 years older than that. The reasons for waiting until you are 50 is no ones business and is irrelevant when compared with the importance of giving a child a loving, stable environment to grow up in.
I think you should all mind your own business and try for a change to focus on being kind rather than judgmental.