Google announced a plan recently to offer Chromebooks for use by schools across the country starting June 15. These computers differ significantly from normal laptop computers as they have no hard drive and very little operating system other than the web browser, Chrome. Essentially, Google is gambling on the fact that most users don't need software since they can access most applications online. Apps for the Chrome interface can substitute applications even as heavy as Microsoft Office.
They are also uniquely priced. $20/month per laptop to lease it and get all the hardware/software support necessary 24/7.
So, here is my plan: assuming a class size of 30 students for 10 months, the calculations would be $20*30*10 = $6000 for 10 months of computing. I think a grant or two from various foundations would be able to cover it and I would have amazing technology access in my classroom.
I highly recommend this option to others as well if you are looking for a cheap way of getting access to the world of the Internet and its applications in class. I think this is going to work out very nicely.