I bought a, "late 2006," MacBook last May from PC Connection, who have been in business for 20+ years. They were about $300 less than Apple's on-line store, plus they included shipping, and a nice carrying case. That is even considering any discounts I qualify for at the educational version of the Apple Store.
PC Connection did charge sales tax because they ship from a warehouse facility in Wilmington, Ohio, and I live in Ohio.
Something you might want to think about is if you cam resist being the first kid on the block to have the most shiny new trinket. If you wait, you'll get some really substantial discounts from retailers and the unit you'll receive will most likely be more reliable because the manufacturing process has had time to be refined.
I waited to get the 1.83 GHz MacBook until the Santa Rosa version was just starting to go on sale. The discounts made the MacBook less expensive than any Core 2 Duo notebook machine Dell was selling at the time.