domain Pr4 developed money making site appraisal needed please

[sgllocal]

hi all im in the thinking of selling one of me sites.. its freeskytvonpc.com which is pr4 and is earning.. im currenty using adwords to boost sales.. have had 10 sales so fasr this month and made just over 500usd last month..

but i dont know how much the site is worth? can somebody help me please and maybe give me valuation for the site with domain etc?

thanks
dan