I think it depends on the congregation. In some congregations, especially rural or inner-city ones where the 'friends' aren't very well off, anyone who buys a new car or wears designer clothes is looked down on as 'materialistic' or 'unspiritual', and I doubt that they would be an elder.
In other congs, OTOH, money and status serve as social lubricants that help a man climb the ladder. (Bad metaphor, but you know what I mean.) Professional experience and education are sometimes helpful as well; commenting, writing talks, and keeping up with all the WTS doctrines and regulations are fairly trivial tasks compared to what's required of an average professional in the business world.
P.S. In relation to ithinksee's comments... senior bethelites, COs, etc get peanuts from the Society. OTOH, they have a great asset to share: status. So the well-off JWs buy the COs/bethelites meals, invite them to their houses, even give them cars. In return, they get the status benefits of rubbing shoulders with the bigwigs. It's basic human nature.