That is true and not true at the same time.
"True" part is that yes, Claro has what they call "prepaid kits" for about 300 pesos, with 100 pesos of airtime. On the other hand, I was recently made aware that these kits are available to people with Dominican cedula only. They cannot sell these kits to foreigners with passports. If they do, they are charged back by Claro the full amount of the phone. Many dealers still sell them, though, because they are not aware of the ramifications, and have not noticed that on their commission statements from Claro yet. This comes from a big dealer that previously sold lots to tourists in Bavaro/Higuey area.
You can still buy a SIM activation (but at the same price as prepaid kit, 290 pesos, it's a daylight robbery) plus a phone -at 600-800 pesos additional for the basic phones. With that, you are better off buying from Viva, where activation is just 100 pesos and they unlock your phone for free.
But if you get to buy from Claro dealer the prepaid kit for 300 pesos, lucky you, but don't count on it as something certain.
You also have option to buy phone under the name and cedula of a Dominican, but then you won't be able to activate features and services on that line yourself (like a Numero Super Favorito for free 5-minute calls).