2.4GHz, 20-inch iMac, $889 after rebate
MacConnection.com has the 2.4GHz, 20-inch iMac (model no. MB323LL/A) for $959, which is already about $18 less than the lowest price we could find anywhere else, and until 5/31/09 use this $70 mail in rebate to drop the price down to $889. FREE shipping is included and sales tax applies for residents of New York state.
The refurbished model of this iMac can be purhased at Apple's online store for $849 with FREE shipping.