[l0jec]

Since you mentioned that you will be using a web front-end for the scouting input, have you considered using personal devices such as smartphones rather than purchasing dedicated devices such as netbooks? This may also allow you to bypass the ethernet to 3g router setup you described.
While a good Android phone may cost more than a $300 netbook new, you may find that many of your students interested in scouting already have an Android or iPhone. The only upfront cost may be creating a mobi type page in your web front-end to render nicely for the devices if the current one is too cumbersome.