Just do what we did, take your time ordering spares, get the SMT to try to recover the cost of the damage from the parents, you should always be able to find out the last logged in user, they are always the culprit, even when innocent! We made a point of having a huge pile of damaged laptops just inside the door so anyone coming in saw them and asked. We never deliver the repaired ones back to department, they have to come and get them, this reinforces their duty of care over the laptops.
Take your time replaceing dead batteries, make sure you bulk buy, we found the best source was XMA, both for batteries and power supplies.
do a presentation to the smt showing relative spares costs and life issues, along with a projection of the maintenance costs for 3 years and show them login times for a room full of laptops compared to the login times for a room of wired PCs.
Point out that frustrated kids, having to wait long times for logins will do more damage than those that are engaged straight away. Sorry if I lapsed into Teacher-babble, surrounded by it all day, even earplugs and Loud Pink Floyd do not keep it all out!.
You will win purely on the financial front, cos they will not understand the technical issues, they will think they do, just make sure they don't.
We have a room of laptops trying to print wirelessly from them to an A3 colour laser printer set at 1200 dpi, A3 sheets of loads of colour photographs, they are lucky to get three or four in a lesson printed, plus it stops nearly all the other laptops in their tracks. Do the sums for the amount of data flowing from the laptop to the wireless point, to the servers and back to the printer and show them where the bottlenecks are.
Another thing, we found the most reliable method of configuring them was using windows wireless configuration rather than the utility supplied with the wireless card.
Good luck