Small network of 7 sites, 4 of which are PR2, 3 of which are new sites at PR0. They're all related to eachother in their main category and link to eachother. One site was started in 2008, 2 in 2009, 3 in 2010, and 1 in 2011. Sites have averaged a little over $100 a month for the last 3 months, $70-$80 a month for about a year prior to that (Adsense, combined across all sites). I have raw server logs, Adsense custom channels, and Google Analytics for every site since it's inception. (with the exception of the site started in 2008, which only has raw logs starting in the end of 2009, it has the other logs in full though) Would $1,000 - $1,200 be a crazy number to value this little network at ?
I would value it higher, simply because that's a year's revenue, personally I would value it at three year's revenue so basically min. $3,500. You did say it's only the past three months it's achieved $100, but I would assume that it's only going to stabilise or increase. I try to keep data on everything too but if I get owned by a host then it can really screw things up(my back-ups were on a laptop that had to be sent for repairs and they wiped the HDD).