Welcome redjennphd
I believe you need 50 posts PLUS 20 rep points as well. Yes, you can 'pad' your post count but you still need to make some quality input for people to give you some rep points.
BUT, if you look at my stats...I only have 28 posts and yet I have my own picture. There is another secret way!
Look at the top of the page. It says "To make a contribution to help us with hosting fees, cost of the board, and addition of a chat room, please
click here. Thank you to our
generous benefactors".
With a contribution, Jenna gives the benefactors some special stuff....a customizable avatar is one of the things. Cool eh?
Anyway, it's not really a secret. I hope more people give something to compensate the great job they do here! It's really worth it!