Game value tracking

Hello everyone,

as my collection grew over the years I started keeping track in value of my games. I am not interested in selling but it's still good to know how much, approximately, everything I have is worth and what might be going up in value (GBA games seem to be) if I have to sell them off.

So my question is this, what is a good site too look up games and see how much they are selling for on average be it CIB, new or loose? Till now I have used PriceCharting.com, I just want to know what other sites, reliable sites, are there out there. Just to make it clear I am not looking for price evaluations, just sites that keep a track of game sales etc. to keep my spreadsheet nice and tidy.

Cheers and lets keep physicals alive.