Consiglio: If you are a woman buying work boots, slippers, or any other non-heel type shoe, always buy the men’s version. Its almost guaranteed to be half the price or more.

Men's smaller sizes go on sale at a very fast rate. To know your men's size, all you have to do is subtract two from your size. So, if you are a women's size 7, you are a men's size 5.
I once got a pair of men's Land's End mocs for $6. The exact same shoe in womens was $60.
Disclaimer: This is in American shoe sizing. Not sure if it works in the rest of the world.