Well on it's own the domain is pretty much reg fee. I just don't see much value in it. Se7ensins.com is way way way to hard to remember and that hurts the brandability factor.
Now that aside you've build the site up into something more than just a domain and that is where your value will come from. For the most what you have looks good ... on paper that is.
A $500 a month site that is PR4 with about 1,700 unique vistors a day ... is easily valued at like $18,000 to $30,000.
However this site is a site built up around xbox, ipod and halos mods. Some will see it as a gaming website and instantly lower the value based on the fact that the gaming website market is extremly saturated. Some will see it as a hack website with TM and other legal related issues and those people will immediatly see the value as much lower due to the potential legal troubles.
Now all of that being said, I will say if your site is earning you $500 a month on google ads you will no doubt make way more if you change your ads to something more relevant to the market and something that doesn't suck ass to put it bluntly. GoogleAds for the last year has just really not been good to many people in the mainstream market that I know. They've slowly but surely been switching over to other type of ads and it's been paying off for them big time.
In the end I would say your site is probably worth about $5k for a quick sale or if you make a few adjustments, about $10k to the right buyer. You could increase that greatly just on what you earn yourself, but that would mean finding better ad programs and to stop using Google Ads which has historically a VERY VERY VERY low click through ratio. The ads are for lack of a better phrase ... done to death. I would suggest something like PythonMedia.com. Their get paid to drive ads work really well for most mainstream sites and have an unusually high payout.
