Mvat selling buying locally and selling out-of-state

Can anyone guide me as to what is the best way I should bill my client? My company is registered in Maharashtra for CST and VAT. Now, I am buying & manufacturing goods in Maharashtra. Therefore, the manufacturer is going to charge me VAT. After paying that bill with Vat, I am shipping & selling that good to a client in TamilNadu. What should I charge to client in Tamilnadu for getting best benefit without loosing my profit margin? I know I have to charge CST. And, if C-form is not available from client, I believe I can charge 12.5% CST to client in TN. Would I be able to offset VAT with charged CST? If I have to pay both, I will be at a loss. I don't want to end up paying 12.5% VAT + 12.5% CST = 25% total Tax. Or Should I increase selling price/value to compensate for my local 12.5% VAT? Please help as I am confused and don't know how to bill the out-station client.