Not sure to what you are referring with that "10 dollar difference".
I'm not in the US, I'm in Eastern Europe. The SMSL IDEA is 73 GBP (94 USD) on Amazon, whereas the Sabaj Da2 is 48 GBP (62 USD). That's nowhere close to a 10 USD difference.
For comparison, the SMSL IDOL+ is 33 GBP (42 USD), the SMSL X4 is sold on the German Amazon for 42 EUR (48 USD), and the FiiO K1 is 36 GBP (46 USD).
Sorry, my mistake. I was not looking at Amazon rates. I was looking at AliExpress rates.