Airserver allows you to stream your ipad or iphone straight to your computer. At just $4.00 per computer, it is dramatically cheaper than Reflector. My initial tests show very promising results. The week-long free trial is a great way to start. Try it out and let me know what you think.
The potential for classroom use is huge, just make sure you avoid the urge to PowerPoint-ify your ipad. Focus on the fact that you and each of your students can share collaborative work, creativity and synthesis.