This is the correct information. As of July 2022, the last time I worked as a volunteer at the Pilgrim Office, the fee was €450.
But, you can write to that e-mail address, and make your specific request. Someone will get back to you. If the date and Mass you ask for is not already subscribed to by someone else, they will convey instructions for payment.
FYI - Individuals and groups who do this - pay for the botafumeiro to be used - are provided preferred seating up front, in one of the side apses. Otherwise, it might be difficult to get in, or to obtain a seat with a clear view of the Botafumeiro.
The Botafumeiro only swings for free on Catholic Holy days and major solemnities. There is a calendar of these days on the Cathedral's website. Check here:
https://catedraldesantiago.es/en/liturgy/#botafumeiro
At all other times, groups or individuals must pay for the Botafumeiro to be used. NOTE: The Cathedral is not making a profit from this. The eight men who pull the ropes - Tiraboleiros - are paid for each ceremony. Hundreds of years ago, there were seminarians or other religious workers who would perform this service for free.
I had the honor of being asked to be a tiraboleiro for one Mass in 2022, when they found themselves shorthanded. I was working at the Pilgrim Office at the time and am very well known to everyone there. So, the request was an easy one. Having sat under the swinging Botafumeiro many times over the years, both in front of the altar rail and within the altar rail, actually being part of the ceremony was a HUGE honor and privilege.
Hope this helps,
Tom