Do you want to check them out in the store first, or have you already done that? If the latter, there are several options. Amazon runs $100 mail-in rebates, looks like there's one still going on. The online Apple Store http://store.apple.com/ carries factory certified refurbished units (with same one-year warranty as a new unit, and also qualifies for the AppleCare extended warranty if you like) at good discounts, though there you'll definitely pay tax unless you can have it shipped to Oregon. PowerMax http://www.powermax.com/ is an indie authorized reseller in Oregon. They don't have a real showroom, though, so unless you're actually nearby, it doesn't really change much. You have to call and place your order before you can pick it up. Similar indies are Small Dog http://www.smalldog.com/ in Vermont and ExperCom http://www.expercom.com/ in Utah. Small Dog and PowerMax refurbish their own used units if you're really looking to go cheap. ExperCom is typically land of RAM upgrades at cheap prices and free shipping.

When I buy brand new Macs, ExperCom is usually the place I look at first these days. At any given time, one of these three may have factory refurbished units as well, but more and more Apple keeps these for themselves. I've bought various refurbs over the years with decent results, but that all depends on your comfort level. In my experience with several dozen Macs, the refurbs don't fail any more often than the brand new units. For the iBook in particular, the refurb at Apple is only $100 less than the net price of the new unit from Amazon. If Apple charges tax and Amazon doesn't, then the difference is almost nothing. So the refurbished route may be pointless.

If you want hand-holding for the switch, go to the Apple Store. They're pretty good at that stuff. But, you don't have to buy your computer there to get help from them there. You can always buy it elsewhere then go in and talk to the "genius" folks when you have a question or problem.