The price guide was built for an earlier time. I first noticed the problem around ten years ago, when Baker romance surged on Ebay. I actually managed to pick up a Cinderella Love #25 in vgf at a local mart for around $20 - ie guide - when it was selling on ebay for low four figures. The argument that Overstreet reflects an underlying trend, rather than spikes which can distort, no longer holds up in this day and age, when everything spikes, and spies again. Maybe a computerized program would be able to factor everything in, but a human being would still have to input all the data. Where Overstreet still works really well is as a comprehensive reference.
I guess it will remain so, at least for the next fifty years or so.
When GAtor passes at the age of ninety, we can put his brain in a jar and hook it up to a mike - then Overstreet will be surplus to requirements.