Yes, many NFGs can and do pay info factions to post a GNS for them. It's one of the ways info factions can make a profit. One example you might have seen recently on the GNS is the Gran Confederacy, which is an NFG that used an info faction, Courier Communications, to post its message.
I'm trying to get something posted on the GNS. One info faction has its website account suspended. Another has a site that says it doesn't provide any services. I'm waiting for the third info faction to respond to my message.
I'm assuming the third group is Bothan Media Services, which I have generally found to be a reliable faction. You'll get a cheaper price by sticking with them, since info factions cost much less to post on the GNS.