$1 for Wikipedia?

If every one of us who use Wikipedia regularly donated $1 per year to its continued, non-advertising funded existence, is that enough? Could Wikipedia get by on that?

If we each donated $25 for a 'lifetime membership/supporter' designation, would that be enough? Maybe the money goes into a big interest-earning foundation/trust thingy - virtually gauranteeing it's continued existence forever?

I'll be back with some calcs.