Indeed there could be many others charging less and eventually competition could bring this to as low as "for free". But if that is the case then blockchain bloating with endless OP_RETURN posts would seem unavoidable. Perhaps in that case the pertinent miner fees will increase and thus "for free" will eventually become out of the question. I am not trying to justify our selection of the price per stamping (we are considering to decrease it), but more of trying to point out that it is not really clear how this whole story will evolve.