Hi Judge,
I'm no expert but here are my thoughts...
1. Check the google revenues... $20 is reasonable for the stats... if it's a consistent and honest $20 then thats a good base to start from.
2. I think that the lower the alexa traffic rank is the better. It ranks your site for traffic against all the other sites that it is watching. And the sites that it's watching are only those that have been tracked by using the alexa toolbar.
916,000 isn't bad but not great either. (would be interesting to know what the 3 month and 1 week and change for the traffic rank are, plus alexa can also provide their figures for reach etc - which may be interesting)
To put things in perspective I have a bunch of websites that I've done very little SEO work on and they have been at one time or another 102,000 - 500,000 on Alexa and a bunch of others that are 700,000-950,000 but this is without any work.
3. Hits include the number of items that are loaded on a page. So if you have 1 visitor to a page which has 100 images on it, that can equal 100 hits. So the hits figure isn't very useful. You should be looking at unique visitors. Not only that but some of my sites have many unique visitors, but 80% of them either bounce off on the first page only sticking around for less than a second, or they come from China (and my site may only sell stuff to people in England).
These geographic features, bounce rates, time on site, unique visitors rates etc can all be found through google analytics. This is a login feature through google.com/analytics however the webmaster must have inserted a tiny bit of code on each of the webpages.
4. I run a couple of forums and a few of the misleading things that come up with the stats are the number of members and post statistics etc. Especially with a new forum many of the posts will be spam, automated bots etc, all who have used fake details (email) etc to register. A well controlled and put together forum will regulate these new members and moderate the spam.
Take a look at the site and see if it looks like it's been cared for and looked after.
Don't get me wrong, the forum you have been offered might be a gem and well worth buying despite the things I have mentioned above.
But the worst case is that you are buying an unlicenced version of vbulletin which only has 1 member (the previous owner) who is posting under 100 aliases, and the rest of the posters being spammers and the revenue from google all being fake, with the forum on the verge of being blacklisted by google for click fraud...
Just somethings to be careful about - but as with all investments with forums, a more 'tangible' valuation can be made from the domain name you are getting as part of the deal. Are you getting a vbulletin (or other forum) licence? Those cost a couple of hundred $. Then of course the member base and verified emails etc is important (search engine presence etc, Page rank of course important)
Good luck, and feel free to PM me if you want me to check out their forum.
