just wait till the first wednesday after the expo and go to the applestore
Click on the link that says "Apple Refurbished Store" and you should be able to get a current tower for 25 - 45% less than it's current price.
That's exactly what I'd do myself if I had the cash, I checked the prices last week just to see what they're like and there was 25% off a 667Mhz TiBook from the current range and 35% off the older 667Mhz model, they come with a warranty and everything too.
That means that if you wanted the current mid range tower, it would be £1,497, £1,297 or maybe even £1,097. That sound pretty good to me concidering it puts it below the price of an entry level tower with a superdrive as a BTO option.
Plus, being apple you can trust them not to screw you like some of the dealers might do.
Minor Rant Below. Ignore it if you can't be bothered reading
I bought my 300Mhz beige G3 as an end of life deal from a large UK dealer that was taken over by cancom a few years ago. I ordered a mac model that should have been one of the last beige G3s produced in late '97, REV C motherboard, Rage Pro, IDE slave support, 256Mb SDRAM support.
What I got was some early model from the lineup that maxed out at 266Mhz in the UK, wasted £40 on extra vram for the useless Rage II+, they didn't even mention it was a grey import model, we didn't get 300Mhz desktops in the UK till the 3rd revision of the lineup, I was expecting the 1Mb L2 and Rage Pro that the model should have had. I could have got a brand new B & W G3 tower for a little bit extra but all the magazines were saying the 512K cache made it slow and I was put off by the nasty little iMac keyboard and mouse. I do admit some stupidity on my part on assuming I was getting a UK model from a UK dealer but you only expect grey imports from a games console dealer, not a mac dealer.
End of minor rant
Anyway, I think as far as G4s are concerned, staying 1 lineup behind the cutting edge by buying a used or end of life mid range model seems to make sense from a cost point of view. Unless an entry level G4 with DDR is significantly faster than the current 933Mhz model, you might find a good deal on one in month or so and you'll have a superdrive and L3 cache aswell.