I've got over 500 apps, i buy a lot instantly as i want the dev to get more money. Suddenly i dont agree with one high priced game and i'm a cheapskate? Wouldnt say my ipod was a 'bloody expensive device' either.
Yes i dont have 'proof' but if the game is half the price i personally (and not saying this is gospel) think that it'll sell much more. Plus its basic math isnt it ? Lower price for a big name game will mean more sales.
If a few years ago games on the app store were all $7-$10 and the 'cheapest' were $5 then fair enough. But the market has been created that so many people expect a quality game for a buck or two (or wait for it to be free).
If you are a huge fan of Soul Calibur then you probably wont care about the price, for others who are undecided the high price will put them off. We're not being cheapskates, just being practical. If everyone buys this then every other Taito game will be this price, other rival companies will see this and before you know it every game will be $12.