Some of my puzzles are obtained at yard sales and although I have been assured all the pieces are accounted for, I cannot fully guarantee it and do not offer refunds for missing pieces.  I usually put my puzzles together myself or count the pieces, and I always ask the previous owner it they were all there.  I have had very few complaints about missing pieces.  If you are planning to frame this puzzle, you may not want to take the risk, but if you are a true puzzle lover of the challenge, a missing piece does not often matter.  All my previously owned puzzles have been price-reduced drastically for this reason.