When we originally ordered our Macs for work, we had 3 x dual 2ghz G5s on order and allocated. As a registered charity, we qualified for this discount after some wheeling & dealing with one of the AppleStore corporate reps.
Within days of our payment before our bank transfer was processed, the dual 2.5s were announced our order was upgraded but of course, shipment was delayed until the machines were here. (I guess that's why we got ours from that first batch that arrrived in the UK because of the early order)...
Anywaaaayy... I then enquired about the edu discount on those machines and it was not possible, not policy, because they were still in their first quarter of shipping. So I guess for most models, you have to wait until the second quarter of a product's lifespan.
Not that I have much sympathy with your educational needs that necessitate an iPod Shuffle...