I'd be interested to hear how much most ministers 'tithe' straight out of their pay. I know mine does, but not certain how much. The dude who wrote the Purpose Driven Life says he tithes 90+ percent of his salary and book sales. Of course, he's a multimillionaire, but still.
When would enough money be enough? Does the OP or anyone else want them wearing sackcloth and living in a yurt? Is there a cutoff somewhere. Obviously, monks and dudes like Osteen are on the outlier ends of the spectrum, but who is to say what kind of life a minister should have outside of his work.
A lot of ministers that I know personally, not generalizing here, are very good with their finances because they don't waste money on dumb crap like some of us do. They are able to have a nice, but not extravagant, home and good cars that are reliable and safe for their families. I did have one about 20 years ago that had a BWM, but he was going through some midlife stuff that he eventually worked through, and sold it. I'm ok with my pastor doing well as long as he is taking care of his other responsibilities.