hey,
I'm not sure why anyone hasn't help you out yet [well, besides the fact that a forum search for the title avatar might help you find some sources...] but I actually just get my avatars from here and other forums that I visit.
Here's a few sites that i have bookmarked that can help:
http://avatarity.com/
http://www.avatarpage.de/
Google images - search for avatar [subject of avatar here]
and that will definitely lead you to other websites that have avatar collections too.
[seriously, searching google for anything will help ya out
]
And of course, there's the DIY way of doing it in the progs mentioned previously...If you're taking this route though and aren't into image editing, it will take a bit of time and effort of course to learn, especially if it's animated avatars.
catcha back on the flipside,
keyshawn
PS - although you didn't state it, it should be stated for reference that the TFP avatar policy is in the guidelines and forum rules.