On more than one occasion, from more than one person, and in more than one place, I can recall somebody saying to me, "Say hi to Hashem for me" as I headed off to the synagogue, or when I was discussing which synagogue I might attend on a given day. Some of those comments were no doubt in jest, but regardless of which ones were and which weren't it reveals an interesting topic of exploration, praying for somebody else. Praying for somebody else, not in the sense of asking for healing, but actually praying in somebody else's stead. Tamar Fox, an associate editor for My Jewish Learning, authored the following article here about paying to pray. It's well worth reading.
An idea that occurred to me, and one on which Tamar touches, is what I've termed the "agent factor." While I don't want to make too broad of a generalization, the majority of American and likely world Jews are unfamiliar and uncomfortable with the structure of the siddur or are not equally uncomfortable with prayer. The discomfort with prayer itself is for individual exploration. I believe however, that we owe it to our communities to teach the siddur in a way that allows people to access it, and its rich history. With enough quality information, I think that the need to pay somebody else to pray would become obsolete because people would not be worried about facing public embarrassment when entering a prayer space. To read a bit more about that, here's another good article: DavenSpot
So while "say hi to Hashem for me" might not always be a serious remark, the duty falls upon us to open prayer to everybody without it having to cost a cent.