Ramien first hears about radio from a visiting priest. It's one of the big advantages of being a Desnan - that even though the church is spread far and wide across the globe, wherever they choose to meet and pray, it doesn't take that long before some of your brothers and sisters in the faith will drop by, to see the sights or get the news or just take a look at what the stars look like from there. Ramien has never connected as much to Desna's aspect of travel as some of his contemporaries, but even he has done his fair share of traveling, and those who do so resonate find her aid in moving from place to place. In this case this takes the form of a fellow voyager he met a few years back teleporting in out of the blue one day, eager to show off the latest marvel catching the inner sea by storm, and it only takes a few minutes of being enthusiastic because they are before he catches on to their meaning and is an instant convert. Desna loves to encourage travel, delighting when people meet new acquaintances and encounter new ideas and societies and generally get a chance to see other ways it is possible to be, but it has long been a sorrow of their church that it is simply impractical for most people to travel to the point that they never even leave their home village. It's better than the places in which it's forbidden, but you're only so free to do something if the costs of doing so are high enough that few people actually do. It is this tragedy that he seeks to counteract with his personal accounts of far-away locales and his comrades do by making sure at least someone shows up at a small town to tell them about the wider world, and it's this tragedy that the radio has the potential to alleviate.
The receivers aren't cheap to construct, per se, but they're nowhere near as expensive as even the least expensive of magical items - to the point that even a moderately well-to-do shopowner can purchase one without feeling too much of a hit, or groups of farmers pool their funds to purchase at reasonable cost. It would be better if they could speak loudly enough that you just needed to be nearby to listen in and purchasing a few would be enough to let his whole congregation listen, but you can't have everything you wish for. After a day of joining his brother in listening to the programs late into the night, Ramien purchases the materials to construct a dozen of them out of his own personal funds. Some of these will go to small villages nearby who don't rate their own full-time priest to do prayers, but a few he saves, for himself and his fellow clerics and anyone who's curiousity about the world beyond Kenabres would otherwise be thwarted. Some day, he thinks to himself, every family will be able to have one, and the world will be that much more connected.