It's common knowledge that a "base price" alone is not accurate enough to value most games. A specific game may fetch a lot more than the base price common to its family because it is hard to find a copy of it. (This is particularly the case with collectors who want to have a complete collection of games for a particular machine - games considered hard to find fetch a lot more on the open market.)
The next measure affecting the price of a game therefore is the "chance of finding it". We categorise this chance as a decimal number between 0.1 (the Acorn Electron disc version of Codename: Droid) to 100 (the PS2 disc version of Fifa 07).
With 103,149 items (and counting!) on our site, we haven't been able to accurately work out the percentage chance of finding every single item - but the form below will illustrate the concept for the ones we have assessed. Choose a Machine Type, a format and the name of a game. The Base Price, and the % Chance Of Being Found will then be reported...
That's not the final valuation - that's the valuation when the % Chance Of Being Found is applied. The valuation may be artificially high at this point as further factors which reduce it have not yet been applied.