dont forget about the CPU HSF for it (usually Barebones dont come with one), optical drive, HDD, and some SATA/IDE cables if you get OEM or dont have any.
not really, its only about $100 total for what i have listed
Pick up an 9800GT for now for about $130, and SLI it later.
the One you picked is $660, then + $230 for the rest
and comes to a total of $890.
Didnt you said you have a budget of $1000?
or do you want to go as cheap as possible?