Come on guys some of this is parts cost and quality also. A quality and purpose built chassis that reduces unwanted vibrations costs and takes engineering. Some use $250-$300 chokes from Lundahl and use 5 of them! Some use $15 resistors and $150 caps in key positions. Some use very high quality circuit boards. Some use high end trannys that can be very expensive.
Some use Opamps at $35 a pop. Some use the best wire at $4 - $10 foot. Some are hand made one at a time taking up to 5 days to complete. Just the power supply in a well made high end dac will have parts cost 100x the Topping dac. Now we can talk about the use of high quality input and output jacks, IEC and such. I could go on and on, but you get the point.
Some use Opamps at $35 a pop. Some use the best wire at $4 - $10 foot. Some are hand made one at a time taking up to 5 days to complete. Just the power supply in a well made high end dac will have parts cost 100x the Topping dac. Now we can talk about the use of high quality input and output jacks, IEC and such. I could go on and on, but you get the point.