You might check the service discussion section. I think i seen a thread about avatar campaign overviews there. You can see all the sites hiring avatar users
I believe this is the thread you are talking about :
https://bitcointalk.org/index.php?topic=1087042.0But no active 'avatar only' campaign with bitcoin payments.
If you want to book it for one or two weeks, then the price will be $3 per week.
The last avatar campaign I remember, was bitcointalk.club's campaign. They paid $2 for a week of participation. So, I like to suggest you to set your fee up to market demand to attract an advertiser. Good luck.