I was just there a few days ago buying SS tube, and they has a bunch of different sheets of perforated stainless steel. I'm sure they will have what you are looking for. I've bought sheets in the past from Online metal store, and from Small parts they are owned by Amazon now. I found both to be reasonably priced for Perforated Stainless sheets.
I'm not going to tell anyone what to do, but most large false bottoms are made from 1/16", not 1/32. If you go that route, you'll need a very good support structure, something like a grid on 3" centers.