For drilling SS and other hardened metals, I have always used a cobalt bit at slow rpms. (Not a cobalt plated... You are looking at ~$30-$50 for a cobalt bit...) You won't find them at a big box store though, they will be cheap plated imitations...)
I would recommend Bosch M42 Grade, which is 8% cobalt... (Yes, it is different from cobalt plated, even though it is not pure cobalt)
It will last you a long time if you take care of it and will eat through your hardened metals...
Bosch bits are boss! When I worked in other countries, I would get them straight from Germany. I recall drilling concrete in earthquake prone Chile. The hardest concrete that I have ever seen. It would eat American percussion bits alive! 1 bit per hole...
An old Chilean man ordered me some from Bosch. 1 bit drilled several hundred holes and was still great.
You pay for quality, however you get what you pay for...
My experience, YMMV
Good luck!
