full member around 0.07 - 0.15 BTC (newly full member to near full member)
Hero is more than 0.4 BTC
there are no official price for that account because it's free market and everyone can offer their account to other user, with their own price
I think sr.member is best for signature campaign, hero's rate is just slight ahead sr.member
I don't understand why anyone would want to buy an old account unless the use is for sig campaign spam or some other nefarious scam.
they want try signature campaign and make profit as soon as possible (not wait 4 or 9 months), so they buy an account.
that's why we saw many non-constructive post made by full / sr.member recently, because newbie behind those accounts didn't have enough knowledge about bitcoin