I don't think that Roma has money to recruit Ronaldo, it wouldn't be absolutely an easy operation. Ronaldo engagement is really high for Roma, so I think that he will end his career in Man Utd, there are only few team that can afford him. (imagine if PSG will brought him to its team, Messi and Ronaldo will play together
Why do you doubt Roma to sign Ronaldo? Do you think Roma is a poor club?
Personally, I'm sure Roma has enough money to recruit Ronaldo. But it may be difficult to ensure Ronaldo because Roma doesn't play in UCL competition next season. Moreover, there are several big clubs interested to sign Ronaldo as well (Bayern Munich, Chelsea, Real Madrid, PSG). I assume Ronaldo will choose a club playing in UCL, he always wants to play in the highest competition in football.
About PSG rumor to sign him, I am not really sure that Ronaldo wants to play together with Messi in the same club. I guess Ronaldo prefers to play in a different club, he never stated to play together with Messi.
Roma does have quite good finances when compared to Inter, and it is very possible that Roma meet the salary that Ronaldo wants.
But the biggest problem is like you said Roma don't play in the Champions League competition, it became a strong reason Ronaldo would
reject Roma's offer. Because we know Ronaldo has big ambitions to win the Champions League trophy, so the possibility of Ronaldo returning
to play in Serie A is very small, if we look at the clubs that want Ronaldo are most of the rich clubs that play in the Champions League.
There is no doubt that Ronaldo will never want to play in the same team as Messi, so it is certain that Ronaldo will not accept an offer from PSG.
For Real Madrid they focus on regenerating their players, so it is unlikely that Real Madrid will be interested in bringing Ronaldo back.
Then we know Ronaldo seems to really love Man United, so I have a little doubt he will choose to move to another Premier League team.
So the most reasonable is Bayern strong candidate to be able to get Ronaldo, but Bayern management have said there are no plans to bring in
Ronaldo in the near future. This means that Ronaldo will most likely stay at Man United until his contract runs out next season.