Why stop at thousands? If simple and small enough, railgun grains-of-rice sized probes at every "near" object in the visible galaxy and create a million node n

Why stop at thousands? If simple and small enough, railgun grains-of-rice sized probes at every "near" object in the visible galaxy and create a million node network to relay and repeat back to earth. Get the cost down to $100 each. Time the launching to say once a day so they travel behind each other as repeaters. Then they only need small transmitters/receivers with small power sources.