So you don't agree with surrogacy full stop, or am I just being obtuse?
What if a gay couple want a child that is a part of their genetic heritage and don't wish to adopt or foster? It's very difficult for gay couples to do either from what I've heard. Your gay friends must live in a very rare local authority area where they are very willing to let them foster or adopt children.
It is unlawful for any local authority to discriminate against gay people as adopters or fosterers. I work for several local authorities who are proactive in seeking gay and lesbian couples and individuals to adopt and especially foster. You don't want to believe everything you read in the papers!
I don't believe in paid surrogacy no. I simply don't understand how paying someone (usually desperate and in a third world country) to rent their womb is regarded with any less abhhorence than we would regard, for example. taking their kidney for payment (as opposed to willingly and freely for a friend or loved one donated).