What's the deal on importing Chinese CNC lasers into the US?

Had someone tell me they tried to buy a whole system, table/laser/controller and all, but it got caught by customs, who wanted to assess far more import duty than it actually cost, based on what they estimated its value at. Had to let it get sent back and resold because of that.

From what I guessed, the mfg tried to mark it as "gift" (common scam, a gift isn't subject to import tariffs) but Customs didn't buy that for capital equipment, and, lacking actual documentation on the price and annoyed by this attempt to game them, threw out an excessively high number for its value.

I don't know if that was the case. What IS the import duty on CNC laser systems? Is it commonplace for Customs to ignore the stated price and arbitrarily assess a value on their own?

Is there currently some sort of allegations of "dumping" such a product here below cost that might cause Customs to use a retaliatory tariff against Chinese sellers?