This is the quick review and compare between different spot welders you can buy them in the links below
This is a comparison, all of them are working above expected
Aliexpress: https://bit.ly/2H5ZlMW
https://bit.ly/3lT31ke https://bit.ly/3nTZEev
Ebay: https://ebay.to/3nSnszn
Amazon: https://amzn.to/3nSnIyl