They aren't the same as competition kettle bells per se, but if you are looking for cheap, solid kettlebells, I've had good luck with the cap enamel coated bells from amazon.

They come in lbs rather than kg, but 35# is $43, 50# is $78, and 70# is $102. All with free prime shipping. https://www.amazon.com/dp/B003J9PT82/ref=cm_sw_r_other_awd_NvJVwb5Y6DSS8