Get Life time version of Instachamp
They had lifetime deal on appsumo but its not more available there any more.
Each code comes with 25000 message per month with 25000 contacts
If you want you can purchase upto 3 codes.
I have managed to get 20 codes . Once sold GB will be closed.
If you can even buy extra codes and resell to your clients.
Note : you wont be able to use credit points or discount on this product as we have limited amount to cover the cost of the product.