Earlier you were asking for an appraisal... I can vouch that I sold a reddit account with a little over 1000 karma and 5 months old on this site for $10. I sold an account with around 2000 karma and 5 months for $15 to a private contact. I imagine if the 7-year old ones have that much or more karma they'd be somewhat more valuable.
I also have a few reddit accounts for sale - If OP or anyone wants to buy 5, 5-month old accounts with little karma as a bundle for around $10 to farm for a net profit of around $40 (if they sell for $10 each at 1000 karma) I will sell them for $10 as a bundle or at $2.50 a piece separately.
I also have an account with over 1400 karma and 5 months old that I would be willing to negotiate prices with - PM me if you're interested.
Sorry for the personal plug - but reddit accounts are my specialty!