Welcome to the site.
Rope is an affordable commodity that can be easily purchased online or at hardware stores. Most guides recommend using 12mm (or 10mm) rope; however, it's equally important that the anchor point can support at least three times the weight of the person for full suspension (a good anchor point is also essential for partial suspension). For rope or ligature material, many guides suggest using polyester or polypropylene, as polypropylene is strong, resistant to stretching, and smooth. Keep in mind that every rope is a little different, so testing for strength and stretch is important.
But people have definitely used non-rope materials for
partial like
ties,
leashes, belts [
1][
2][
3],
bedsheets,
scarf, etc. Depends on how strong the material is I suppose and the method as a lot of people
fail with partial (not everyone, of course people do succeed including some well known/famous cases like Robin Williams, Kate Spade, Chester Bennington, Michael Hutchence, Anthony Bourdain, etc).
With how available, easy and inexpensive getting a rope is that may still be a possible thing to consider if you wanted to decide to go with something more reliable.
These posts
may be helpful [
1][
2][
3][
4] to help with your research as well as to locations, as would the
Hanging MegaThread.
With whatever you decide, I hope you find everything you are looking for and get peace & serenity.