IMO, the current price of a first-class domestic stamp should be right on the homepage.

On Google, in the suggested search box, if you type:

"how much is"

The first option to come up is "how much is a stamp"

I've performed this search myself many times because I don't mail letters often, but when I do, I go to the junk drawer to get a stamp, see a sheet of $0.42 stamps and wonder, "is that how much stamps are?" It's not. But to find this out, I had to do a search and dig.

HOWEVER, the first place I went was USPS.com, and since it wasn't right on the homepage, I went to Google instead of trying to browse around their site aimlessly.