I recently came across plastic and inexpensive (how’s $1.50 each!) plastic milk bottles. They look just as good as the glass ones but they’re affordable. Shop Sweet Lulu sells them. They’re 5.5” tall and hold 8oz of milk.
I think it would be fabulous to serve a cookie bar with milk for guests at the end of the night. You can also find striped and polka dot straws in a rainbow of colors to put in each bottle at Shop Sweet Lulu.