Pretty much every thrift store has these.
Try to get the 100% silk ones.
Alternately, have someone with a lot of ties
purge their closet.
I used eight ties. You may need more or less depending on your dimensions. You should be able to estimate this by measuring the width of each tie about 1/3 of the way up from the bottom, doubling it, and making sure that all of them added together is bigger than your hip measurement (assuming that is your maximum dimension).