Prices went up when investors came in and increased the price after Tata's preliminary bid of 455 pence a share and before it was challenged by Brazil's CSN, he said.
"But we have to pay for getting the company... as a prudent management, we had taken a view that we would not go beyond a point... we did not reach that point... had we reached, we would have walked away," Tata said.
He dismissed suggestions that the group had overbid for the acquisition of Corus, saying: "Overbidding or not is subjective when it comes to a judgement call."
Giving an analogy of real estate prices, he said what could have been considered a fair price two years back for a flat may not be the same now and added that steel company prices were only going up.
Tata Steel vice president (finance) Koushik Chatterjee said that the offer puts an equity value of $12.1 billion and enterprise value of $13.65.