I think paying just to have an avatar is a bit silly to be fair, this is certainly the first forum I've come across with such a policy.
If your concerned about additional bandwidth costs (minimal as they are with 10kb or so files
) then simply allow people to host them elsewhere, the function is already built into in VB
In my opinion the RIBnet supporter subscription is basically a donation rather than gaining access to additional features. I mean, very few people need a 500 pm limit
And I very much doubt the ability to have an avatar will make more people sign up.
I would suggest a variably donation amount with an acknowledgement in the form of a user group change would be just as, if not more effective in gaining funds when used in conjunction with the existing subscriptions. Apply say a £5 minimum.
The trade subscription is another matter of course, and generally has a purpose other than donating