If there is valuable software, database or other asset that is not currently contributing to the income - or will influence the earnings trend upwards - this could increase the price the site reaches at auction. Similarly, if there is an asset that will cease to exist after sale or a license that will revert or end post-sale this could adversely affect the price. If you haven't provided any of those figures then there may not be relevant notes to put this valuation in better context.
PR of the directory seems to make a difference to price as owners of higher PR directories can often charge a bit more for review/listing of sites. However, that seems to apply only at PR6 and above.
Directories don't come up for sale that often compared with content sites so, because of less data on them we have set our confidence level in this valuation at just 60%
Web businesses currently available for sale at various forums