Just installed the used lcd+digi assembly. The stupid flex cable for the side buttons didn't separate with the glue... Tried super gluing it to the new assembly, really sloppy but it's working. Phone working so far, just charging the battery up.
I've replaced the display assembly on two 920's. I bought the glass, digitizer and LCD in a complete assembly. They are all bonded to each other and it is recommended to be repaired that way. To separate the glass/digitizer correctly requires a thermal separator and LOCA glue and a UV machine to properly cure the glue.
You are comparing apples and oranges... The $100 part on etradesupply is glass, digitizer AND LCD. The OEM screen and digitizer is about $30. You normally don't need to replace the LCD.