Bob, on the starting figure, I disagree. I think I started with like $1-2k. You can start these days with as $500 or less. However, you can't learn very good allocation skills with such a small sum of money, so I'd suggest north of $1k, at the very minimum.
The important thing is to start somewhere. If you wait forever, you'll never do it. Start with small sums and learn. You'll make some, lose some, but you'll learn, I assure you.
It's something everybody should do and understand.