we do a fair bit of stainless sheet at work, guillotine is nice and
fast, accurate. if you dont have the money to buy one then mark it out
and take it to a local engineering mob with a 6 pack near closing time.
plasma is ok for big fat pieces with tricky cuts, but the guilotine is
the way to go. forget the bandsaw. There are some nice blades we have
for angle grinders that are *really* thin... you've got to be precise
using them because if you twist while cutting or push to hard they just
explode. They were made for stainless and a bit pricy, but they are
really good and accurate, and you can get semi-good life out of them if
you use only a little pressure.

You didnt say what dimensions/shape you are trying to cut