Not sure how I'd value mine, I can't see any comparable ones. But then again my main is over 16 years old so has lots of karma, awards, membership to invite only subs with high profile users, mod permissions etc.

I suspect it's diminishing returns once you get past a certain account age and karma count if it's being used to spam or scam. Tempted to sell up and just draw a line under it though, it would feel dirty contributing to reddit after the way they've treated the people who actually generate value for them.