Maybe consider buying an older 12" to 15" screen laptop-
Used, they'll be $50 to $200 on craigslist or ebay... and already may have some software... If they get ruined, just replace them with another used one. Also, chances are they will be faster than a netbook (which I've personally wanted!!).
Only downside I'm aware of might be battery life, but a power inverter isn't that expensive!
~Matt