Ah. I thought you had those Am-Tech step bits linked in your first post?
You can try this set. I'm not sure of the quality, but it is cheap and should do the job fine. But you can search drill bits in the search bar to find other sets. Alternatively, just go to a hardware store and see what they're selling.
Was tempted to get a brushless dewalt but I stopped myself lol. I got these last year, they seem decent.