If you mean the entire cost of becoming a miner in 2009 then it was really cheap at that time since the Computational power (difficulty) was alot lower than this especially from the fact that we could mine a block with our PC which uses only CPU but as the difficulty increases, computers having GPU was uses before now that we are currently using Asic machines, while the cost of electricity also increases with this different machines/computers

Also you should note that you can't singly mine 1btc, at that time the reward for mining a block was 50 btc but currently after the 4th halving which happened this year on April 20th, the mining reward is 3.125 btc.
Bitcoin halving occur approximately after every 210,000 blocks as been mined which is currently like every 4 years

The cost can be estimated.

In 2009, the difficulty was 1 and the hash rate of a CPU was around 3 MH/s.

The average time in seconds takes to mine a block is estimated by: time = difficulty * 2³²  / hash rate

So, the time to mine a block of 50 BTC was about 1 * 2³²  / 3000000, or 1430 seconds. That means, 1430 seconds 6060 50 BTC, or 0.008 hours per BTC.

A typical desktop computer might use 300 watts and at the rate of $0.10/kWh. So the cost of mining was 0.3 kW * $0.10/kWh, or $0.03/hour.

0.008 hours/BTC at a cost of $0.03/hour gives $0.00024/BTC

Feel free to verify my math.

I don't know any resource to show you cost of mining 1 bitcoin in 2009, but there is information for it in 2010. It is related to the forum admin, theymos.

https://www.reddit.com/r/Bitcoin/comments/su7jld/mining_250_bitcoin_with_1_computer_12_years_ago/

1430 seconds is approximately equal to 23.83333 min, but the average time between each block in 2009 was ~ 13 minutes to ~ 18 minutes, which means the hash rate of a CPU used was higher than 3 MH/s. I searched for some old topics and found that types such as Intel(R) The Xeon(R) CPU and AMD Phenom(tm) were giving more than 6 MH/s which is what was mostly used for mining, giving us an average of less than 23 minutes.

https://data.bitcoinity.org/bitcoin/block_time/all?f=m10&t=l
https://bt.irlbtc.com/view/1628.0

That doesn't make sense. If the production cost of 1 bitcoin was only $0.0001 in 2009 and there were 2,625,000 coins mined in 12 months, then the electricity cost was just as little as $262.50 for an entire year?

To be honest this is not the answer to your own question because here you are mentioning Bitcoin's market price, when they made a trade it was a market price, not the production price. The price really can be calculated hehe, at least on my end because I was not familiar with Bitcoin mining and I don't know the production scenarios for Bitcoin such as machine cost, electricity costs, etc, but if we compare the production costs we can say that the production cost was negligible.

But if you have efficient input values here are the simple formulae to calculate the production cost for the Bitcoin.... I've taken it from Reddit haha and confined it with the lazy AI tools so if this formula is not efficient don't get offended just put a note for my knowledge enchantment.

Production cost = (Electricity cost * Electricity consumption * Hash power on that time) + Hardware cost. it's a general formula there are some others but it's quite simple to understand about the production cost for one block reward then simply you can divide the answer by 50 because block reward was 50 Bitcoin.