The Mirrors of Elangir - The Schemes of Raltarn & Tomaz, #1

Raltarn and his uncle are entrepreneurs, struggling to make an honest living - or failing that, any sort of living - as Raltarn scrapes together a dowry for his fiancée Shanu. Shanu's father, tired of waiting, gives Raltarn an ultimatum - double your fortune in three months or the wedding is off. While clearing junk from a dead man's house, Raltarn finds a magic mirror that can communicate instantaneously with an identical mirror over great distances.
The pair could provide him with a dowry - and might give his country the edge it needs in the long war with its neighbour. When the other mirror proves to be thousands of miles away, across dangerous seas and unexplored lands, Raltarn and his uncle decide the risks are worth it, but they soon discover they are not the only ones who see the opportunity for power and profit...