Too little information -- New, used, warranty? From a authorized dealer or on ebay or off the back of a truck? US dollars or Aussie Dollars or Canuck Bucks?
Yer ATA100 simply means a normal ATA/ISE bus (100 MB/s). The drive is 30 Gb in capacity.
Since US$999 with free shipping is the Apple price for this identical configuration new, than if this is anything other than new from an authorized dealer you'd be nuts to take it.
If you mean "Is this a good deal for ME" then we need to know a lot more about what you expect to use the machine for.
I'd wait, or buy a newly second-hand ibook. They are great machines especially if you have wireless internet around the house. RAM of course will make the biggest impact - I'd seriously suggest well over 512, the performance increase is huge with 1GB.
One of these actually arrived at my house just the other day. I also got the free printer, free memory upgrade to 768 MB, and free carrying case (all after rebate of course). Shipping was also free with a rebate. And no tax. All in all, I think I got a pretty good deal! Playing with one of these today is also much better than playing the waiting game!