I am not Catholic, and I believe the Bible is the only authority. There is nothing in there about a requirement for priests to be poor. So I have no problem with a priest choosing to be poor, but that is not a Bible based doctrine. That is a choice of the individual. Again, nothing wrong with it... but it isn't a Bible scripture saying that.
Also, there is no monk the Bible who kept a coin, and stayed in purgatory. The only passage in the Bible that talks of people who are dead, is Luke 16:19, where Jesus relates the story of the rich man and Lazarus. The key there is that we know their rewards had nothing to do with being poor or rich, and we know this because the Rich man talks to Abraham, who by every account we have, was extraordinarily wealthy.
Lastly, the statement "money is the root of all evil", is no where in the Bible.
You are thinking of 1 Timothy 6:10, which says:
"For the love of money is a root of all kinds of evil."
Note, it is the "the love of money", that is the root of all kinds of evil. Not money itself. Throughout the entire bible, both old and new testaments, the key thing G-d is looking for, is what is in your heart. G-d generally doesn't care much what you have, as much as what is in your soul.
This is why you can just as easily have greedy and envious poor people, as rich people. Both can have the love of money in their hearts.
This is why he told the Rich Young Ruler, to give away his riches. It wasn't because all Christian's have to be poor. We know that because Jesus was in contact with many wealthy people, and he never told all of them to give all their money away.
Jesus was buried in a very wealthy man's tomb. He was a Christian. If Jesus had told him to give away all his money, he wouldn't have had a tomb for Jesus to be buried in.
Before Jesus was killed, a woman poured extremely expensive perfume all over him. If Jesus had told them to give all their wealthy away, that woman would not have had that perfume.
Jesus told that one person to give away his wealth, because that one person had the love of money in his heart. And we know this because he went away sad. If we knew that just giving away our bank account, was going to guarantee our soul in Heaven for eternity... we would be jumping for joy on the way to the bank. But this specific guy had the love of money in his heart, not eternity. That is why Jesus told him to give away his wealth.
But that doesn't apply to everyone. Just those who have the love of money in their hearts. Again, Jesus had many rich people who were Christians. And he didn't say that to all of them, did he? Neither did the early church, after Jesus resurrection.
Lastly, just to support my prior statements, you pointed to that verse in Timothy, about the love of money being the root of evil.
That same book, in 1 Timothy 5:17 says the following:
Let the elders who rule well be considered worthy of double honor, especially those who labor in preaching and teaching. For the Scripture says, “You shall not muzzle an ox when it treads out the grain,” and, “The laborer deserves his wages.”
So like I said before... I don't know where Christians get this idea that people who minister, should not be compensated, especially when the Bible very specifically, and directly about people who teach and preach, should get wages for their labor.