If a minyan is needed and can't easily be found, is it OK to pay Jews to attend, who would not come otherwise? And is a negotiation on the price seemly?
Several shuls in my neighborhood have been doing this for a while. I implicitly trust rabbis' halachic decisions, unless there's a strong compelling reason not to. I feel no need to inquire of my rabbi's reasoning as to why it is permissible, especially if he has been doing it for a few years. So, if you're willing to trust my rav on at least half the level as I do, then, yes, it's permissible.
As I know the nature of at least one person who attends this minyan and is paid (happens to be my son), it seems that negotiating the price is also permissible.