Ask HN: Bitter-Free Coffee

Good day!

On most days, instant coffee with milk works for me. However, I have recently started intermittent fasting (5:2), and i find the black coffee to be too bitter. While adding a bit of salt helps, I am on the lookout for coffee that is not bitter, even if that meant i have to learn how to roast/grind, so on fasting days i can enjoy caloree-free coffee.

Currently I am living in Spain, and I could budget ~250EUR. Any suggestions on beans/equipment, and also where to buy? any resources/books (in English) to learn more on this topic?

Thanks much in advance!