Suppose if I had a brother that doesn't daven, and no matter how much you advice he won't daven, but he cares about money so if you give him money he will start davening, and if I kept giving him until he gets used to it and Hashem guides him. Is this permissible?
In my neighborhood, there are several shuls where the rav has paid people to come to shul to daven. I can't speak for the motive of each of these shuls except for the one that I occasionally daven in. Here, the rav has two motives - 1) To help ensure a daily minyan - this is for the need of the tzibbur and 2) For some of these attendants, it's to encourage them to daven, as they probably wouldn't do this at home.
When my kids, at ages 5-12 were in yeshiva, , they frequently awarded prizes (rarely cash, usually candy, lunch coupons, toys, etc.) if they came earlier to daven with the rest of the older boys. They had a similar incentive in summer camp.
There's a rule that's frequently applied to mitzvah performance - מתוך שלא לשמה בא לשמה. I.e., when one does a mitzvah for motives other than just because of the sake of the mitzvah, eventually, because of habit, he will come to do them for he sake of the mitzvah without other motives.
It seems to me that the Mishnah Megilah 1:3 deals with what a city is. The answer is if there is a quorum - ten 13 years old Jewish males - of batlanin, so the place is called a city. If not, it is a village. According to Bartenura, batlanin are people paid by the community in order to make sure the synagogue will have a quorum of 10 men. So even at the Mishnah and Gemarah time, the concept of paying someone to make sure that the city will have a Minyan existed.