There are a lot of variables. Are you talking maxed Zerkers? Also, are you looking to find Zerkers with high non-combat skills too? Also, it depends on the items/untradeables the account holds.
The quote you was given above, isn't really a representation on anything, as that quote has been given with no background what so ever, also, to find a decent Zerker account you will certainly not come across one for as cheap as 80M. Not a chance.
I have a Zerker here [S][$200 Donator] Amazing Zerker Acc. 1740+ Total. 99 Herblore. 99 Str ETC!! which I've currently been offered $300 for. A Zerker's price like this also depends on the seller as buying from non-trusted users will try and sell for a lot cheaper due to a quicker sale, whereas a more reputable user will sell for a higher price based on their reputation.