So, to really make the most out of Roon, one has to commit to a £20 per month/£240 per year Tidal subscription in addition to a minimum < £120 annual Roon subscription - or < £360 all in.
Even with a lifetime Roon membership, you are still implying that an ongoing Tidal subscription of £240 per year is what really makes Roon work.
No. Roon facilitates this with my own library too. It's just more diverse the more diverse the source material, such as provided by Tidal and not just material within my own library.
I don't know about the other solutions offered, but the best feature about Roon for me is that, assisted by, but not exclusively because of, its almost seamless integration with Tidal, I am enjoying a much more diverse selection of music than I previously listened to, other than on radio. This diversity is not me choosing other artists etc, but because Roon offers it to me based upon what it thinks I will like and not just a random selection.
IMHO, the value of Roon far outweighs its cost. Roon lifetime cost me £390 and Tidal Masters costs me ~£16/month. I also bought about £400 of dedicated new hardware, but could have got away with non dedicated setup on what I already had. That gave me 6 zones, but I only use 4 or 5 of them in reality.