Mills was in the A's clubhouse Thursday afternoon and worked out with the club pregame, but he won't officially be added to the active roster until Friday, at which point Oakland will make a corresponding roster move.
The $1 price tag was a technicality of a clause in Mills' Minor League contract with the Brewers that included an out if he was not in the Majors by June 15. Milwaukee was forced to make his availability known to other teams and let him go if one wanted him.
The A's did.
Of the $1 fee, Mills smiled and said, "I thought it was a joke. Whatever they had to do to make it official, I'm all for. I don't take it as a value of my worth as a ballplayer."
The 29-year-old, who has a 7.76 ERA in 15 big league appearances, including 10 starts, was 4-2 with a 1.56 ERA in 14 appearances (12 starts) at Triple-A Nashville this season, including one stretch of 18 1/3 scoreless innings.
Now he's prepping to make a start for a team with the Majors' best record.
"I did read that last night," Mills said, "but you wouldn't know it. First impression here, it's just like anywhere else. There's no pressure, it's just baseball. First and foremost, my goal is to contribute and be a part of it.
"Obviously they're playing really good baseball and they pitch really well. It's fun. You feed off of that. It's fun when you're feeding off each other. It's not a competition, you're trying to hold your own with everyone on the staff, and I think that's a good vibe to have."
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.