Can a sewing machine be used to make a buttonhole even if it does not have a buttonhole setting?

What do I look for and how is it done?

I ask because I am thinking of buying a very inexpensive machine, but it does not have a buttonhole setting. On the off chance in the future I need to make a buttonhole will I be able to do it?

When I used to sew back 30 years ago my machine had cams to create buttonholes.