I think you could probably get away with a 15a switch if you're only buying on Amazon I did manage to find one 21a switch but it's pretty expensive https://www.amazon.com/ELECTRONIC-COMPONENTS-V21-1C6-SWITCH-PLUNGER/dp/B00DED7PQ2/

Personally though unless you need it tomorrow or are outside the us I'd get everything from out of darts or foamblast. when it comes to stuff like it's generally cheaper even after shipping and they're very reliable shops.