I went through my AMZ history - apparently Sainsmart stopped selling UNO R3 clones in 2014, and the alternatives I'd bought since then are also no longer listed.
Aaanyway...as long as the item includes an Atmel "Atmega 16U2" to go along with the Atmel 328P (the classic socketed DIP controller version) you can't really go wrong. The 16U2 is the USB-Serial bridge chip for true R3 designs, where there are also "half-clones" that rely on a CH340/CH341 bridge chip that can have issues with software that doesn't know how to talk to it.
So, looking at AMZ, I'd be comfortable going with this listing...or pretty much any of the $11-12 listings that address that bridge chip issue...
https://www.amazon.com/ePalZoneXP-ATmega328P-Atmega16U2-Arduino-Compatible-Arduino/dp/B0CRF4NC7Y/
Cheers!
Aaanyway...as long as the item includes an Atmel "Atmega 16U2" to go along with the Atmel 328P (the classic socketed DIP controller version) you can't really go wrong. The 16U2 is the USB-Serial bridge chip for true R3 designs, where there are also "half-clones" that rely on a CH340/CH341 bridge chip that can have issues with software that doesn't know how to talk to it.
So, looking at AMZ, I'd be comfortable going with this listing...or pretty much any of the $11-12 listings that address that bridge chip issue...
https://www.amazon.com/ePalZoneXP-ATmega328P-Atmega16U2-Arduino-Compatible-Arduino/dp/B0CRF4NC7Y/
Cheers!