Oooh someone here also mentioned menstrual cups - I use one, and it's awesome! It has saved me so much money over the years, the original cost of it was $60 but I used to use minimum $20 a month, and the cup has a 10 year lifespan. So something that has a 10 year lifespan has paid for itself in three months = awesome!

Would highly recommend them. Also I do use cloth pads at night or at other times when I don't want to use the cup, they're fantastic as well.