I think most sinks are 304L. These days they are usually deep drawn from a blank. I doubt if its possible to deep draw 430 to that depth.
It was just a thought based on the cheap sink being strongly magnetic comment. 'Common application' lists for 430 stainless often include 'cheap sinks' although they may be talking about fabricated commercial stuff rather than deep drawn units (unless the lower rate of workhardening compensates a little for the slightly lower ductility?)...
http://www.stal.com.cn/pdffile/430.pdf
http://www.aalco.co.uk/datasheets/Stainless-Steel_1.4016-430_95.ashx
The 200 series austenitics also get mentioned as a cheaper alternative to 300... http://www.aalco.co.uk/datasheets/Stainless-Steel_201~201L~202~204-200-Series_97.ashx