I still do some work on my 2010 iMac. It costed me 3400 EUR. It will be its 10th aniversary soon. That's 28,3 EUR /mo for 10 years in costs for a piece of hardware that helped me to get a lot of money. This new Mac Pro, the base one, will cost me around 57,6 EUR/mo over 10 years. No monitor included, but if we include the new one, it will be around 106,9 EUR /mo over 10 years. I don't know if it is too much but I see this new Mac Pro too expensive and I am not chosing hard upgrades, but if you go a bit crazy yo can easily calculate 200€/mo over 10y.