The Wall Street Journal has a story about online appraisers, entitled Services Spot Hidden Gems Among the Junk. For those who live far from an appraiser, a service like this might help someone learn the approximate value of possessions sitting in an attic.
I wouldn’t rely on an appraisal like this for goods of high value or susceptible of easy, common replication as fakes.
There’s no disputing, though, that the Olivetti typewriter depicted in the story certainly looks sharp.