Expercom.com has pre-order prices posted along with pricing for upgrades. Who knows if they're accurate, though I would assume so if they are actually taking orders at those prices.
It appears that the Fusion will cost about $250 with the 1Tb drive. From what others have said here, then it would be much of a savings to buy a 3rd Party SDD and boot from that.
The SSDs cost nearly $200 alone. Or, am I overlooking something?