AT150mlx price went up

Discount of $250 vs $450?
You have a strange sense of humor.
Setting $800 MSRP is nothing but a marketing gimmick, IMO, but it may work, who knows.

I would agree the popularity is a major factor. It may no longer be a most underrated MM cartridge.

I just checked: AT150MLX went up $100 both at J&R and LPGear.

AudioCubes2 still has them for $299.

LPGear still sells the replacement stylus for $179.95 here.

When you factor in cost of ownership (replacement stlylus for the price of a Denon DL-160 or Grado Silver), it's still a stone cold bargain.

Strangely enough, the AT440MLa had dropped back down to $119 or thereabouts.