Sean Kilpatrick/CP Finance Minister Bill Morneau speaks at the National Press Theatre during a press conference in Ottawa on May 29, 2018.

"If it was a car, we would say they paid sticker price, they didn't negotiate very much, they didn't get that many deals or manufacturer's rebates — quite the opposite," Giroux told reporters Thursday.

Parliamentary budget officer Yves Giroux estimates the Trans Mountain pipeline and a planned expansion project are worth between $3.6 billion and $4.6 billion, which means taxpayers paid close to the high end of the project's calculated value.

Yves Giroux, the parliamentary budget officer, on Thursday presented an analysis of the overall value of the oil pipeline, which the government purchased from the Texas oil company Kinder Morgan last August.

OTTAWA — If the Trans Mountain pipeline expansion does not go ahead as planned and on budget, the $4.4 billion that government paid to buy the pipeline project will have been too much, says Parliament's budget watchdog.

Expanding the pipeline's capacity will come at a cost of $9.3 billion if the project is completed on schedule by Dec. 31, 2021, the PBO estimates.

But should the project encounter any construction delays or cost increases, Giroux says, "then it's quite clear to us that the government would have overpaid" for the pipeline.

The federal government bought the pipeline from Kinder Morgan in August after political opposition to expanding the existing pipeline between Alberta and the B.C. coast gave the company and its investors cold feet. The government announced the purchase price as $4.5 billion but Giroux reported that after final adjustments, the net payment to Kinder Morgan was $4.4 billion.

Finance Minister Bill Morneau contends, however, the final cost to taxpayers was actually $4.1 billion, after a $325-million capital-gains tax payment — and therefore falls in the middle of the PBO's valuation of the project.

Morneau also contends the government engaged in "significant negotiations" to get the best deal. He defended the pipeline purchase as "a good economic decision."

'Big economic advantage for Canada'

"We can see the significant commercial advantage in the purchase, but also the big advantage for Canadians allowing us to get our resources to international markets, not just the United States, where 99 per cent of our oil is going right now. That's going to be a big economic advantage for Canada," Morneau said.

The Federal Court of Appeal struck down Ottawa's approval of the project in a ruling delivered on Aug. 30, saying Canada failed to meaningfully consult with First Nations along the pipeline route and that the National Energy Board failed to examine how the project would affect marine life. The project is now in limbo.

Given that the 2021 completion date was set before the court ruling was delivered, Giroux says he believes the expansion is likely to face delays and, in turn, financial losses.

A one-year delay in the project would reduce its value by $700 million. A 10-per-cent increase in construction costs would reduce the value by $450 million.

"All indicators point that there will likely be a delayed construction. And construction costs — I think it's also quite possible they will increase," Giroux said.

Morneau would only say it's too early to know whether the 2021 timeline will be met, as work is ongoing to consult with Indigenous groups.

NDP MP Nathan Cullen says he is frustrated the purchase was "rushed," which he believes means Canadians taxpayers ended up with a bad deal.

"It feels to me like they got boxed in and they went and played Texas hold 'em with a Texas oil company and lost, big time," Cullen said.

Conservative infrastructure critic MP Matt Jeneroux said he was discouraged to learn that the Trudeau government could have paid up to $1 billion less.

Watch: Nathan Cullen blasts Morneau on Trans Mountain purchase