You're not going to get a representative response with that kind of question, people with a lot of bitcoins generally don't want people knowing that they do. A rough guide is: the longer someone's been active on the forum the more likely it is they picked up > 1000 when they were < $10. Unless they sold them all at $5 and are still whining about it. Some people also put bitcoin addresses in their footer, so you can go and look up what they're worth on the blockchain, or at least, what that address is worth.
That's assuming that our donation address is our only address...