If you are really concerned, then paying for something within reason should not be an issue. With that in mind, I would suggest taking a serious look at Ironkey USB sticks; models S250 or D250 personal drives. They have locked storage, built in secure browser using Tor as mentioned above. Also has password vault.
I didn't want to post a link here to avoid them seeing a bunch of hits from Eccie sending you over there. Originally Posted by NYr
Yes, ironkey is great. However, keep the portable browser light (without addins), since they may ignore the proxy settings.... thus exposing your location.
Still, eccie should have gone SSL years ago, to make it harder for those surfing at Starbucks via their smartphone, etc.