In 2008 one Chinese company came out with a "tube amp" for $299 USD that was in reality a SOLID STATE amp with a tube driver section. The tube driver section offered virtually no gain but was in the circuit. If you pulled a tube out, the amp wouldn't work. After the deception was found out, these amps were discounted to $99. Below is a link with photos that explains the story of this "tube amp".
What I really liked was Page Two of the linked article, where he describes the conversion of one of these amps that he bought for $30, into a genuine single-ended EL84 tube amplifier. Parts cost would have been several times as much, though.