The price only increases exponentially when scythe and/or bunny ears are involved. Otherwise the rares don't really make the account's value go up a whole lot.
Similarly, the account's combat level have a large influence on it's value as well.
I bought an account with most of those items + scythe and bunny ears for $10. It was being sold that low mostly because of it's kinda crappy stats and pretty high combat level (72).