Anyway, back to the question.
The Japanese and US games will probably rise more by percentage as they will be more difficult to get hold of in MINT condition. The Clamshell games will rise steadily but will probably level off some time next year.
Only the really rare stuff will raise to high values, i seriously expect a PR to go for over £200 in the next year. <img src="graemlins/loco.gif" border="0" alt="[Loco]" /> Although it is not the greatest game, it is just so hard to get hold of, and because the 39 Clamshell set is attainable (unlike many formats), there will be some serious bidding going on for them, assuming that they go to auction at all.
Other games that will rise in value quite quicker will be - The Last Blade, Gals Fighters, Picture Puzzle, Shanghai Mini, and Neo Bacarrat (all Clamshell editions). One of these will probably hit the £100 mark soon.
Evolution and Faselei have topped off really, and i think the price of these will remain fairly static for the next year or so, simply because they are fairly easily available.
And prices now? Well, i certainly think the Edge article has brought a lot of other people into the NGPC scene, and personally, i have already seen prices rising in the last month.

More people, less games to go round, bigger bidding wars, higher prices.
We will see how the future compares. <img src="graemlins/spock.gif" border="0" alt="[Spock]" />