Titleist offers a 'buy 3 dozen custom Pro V1, get 1 dozen free' this time of year. With an effective price of ~$36.75/dozen, I usually stock up my entire season's worth (12 dozen).
Last year I played custom #45 to signify our 45th President, with "Make America Great Again!" emblazoned on each ball. This year I will still be playing a 45, but I now have our President's 2020 campaign slogan "Keep America Great!" printed on them.