Value in these regards is generally related to supply and demand. I am unaware of a marketplace for selling IG accounts. This thread seems unusual.
Where were you thinking of selling this account?
Why are you selling it with these levels of "engagement?"
Why not simply use it to make money the original way you intended when creating this account?
I don't think many people will be interested in buying this account, but generally the best thing to do would be to find where others sell these types of accounts, and see what the going rate is. I think others have pegged the value of your account pretty close to what it is worth ... very little. You should probably find a better way to attempt to market it than like this. I doubt you are getting many PMs for this, but good luck nonetheless!
For posterity you should be able to get anywhere from $0-20 as others have indicated for this essentially non-valuable account.