So my Nikon D5100's are 16mp portable scanners.
If space is at a premium when you travel, I agree with Wales and Tech, a camera can and will do the job. Of course, if you get one of those odd sized receipts, then you're going to have to crop and probably resize the image. In that instance, I can see the advantage of a portable scanner as a time saver if you're not familiar with whatever photo editing software might be on your computer.
Back around Christmas, there was a discussion here about a portable scanner but I'm drawing a blank on the name, mydesk, desk something...I can't remember and it's driving me sane.
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Have PV-500 & willing to travel.
"Answers are easy. It's asking the right questions which is hard." (The Fourth Doctor, The Face of Evil, 1977)
"Somedays you're the pigeon, somedays you're the statue.” J. Andrew Taylor
"I have never met a man so ignorant that I couldn't learn something from him." Galileo Galilei