Although Sonic Adventure is currently set for a December 17 release, that's always likely be pushed back again. Since I won't be playing it until this time next year anyway, they can postpone it as often as necessary as far as I'm concerned. Just so long as I can be assured a flawless product when I do sit down to my first experience with Sonic Adventure...
For the record, the system will start at ¥29,800...roughly $220 in US currency, and that price includes the 33.6Kbps modem. Not bad at all for a brand new console, and it'll only go down from there. (Although that isn't the official US price, SoA will probably keep it between the $200-$250 range.)