Keep in mind, that the new iBooks will almost certainly be the same price or even cheaper. VERY few instances Apple will update the product and up the price. The new Mini is the ONLY item I can think of that did this, as the Intel iMac stayed the same I believe. But if your store won't get it for a month, then its up to you...Personally, I'd wait, because an Intel iBook would prob KILL a g4, even with a solo proc.
Edit...maybe not KILL, but it would probably run a few circles around the g4