You can get decent hammocks with tree straps at Amazon for 19 to 35 $ depending on size. There are several brands, that all make a very similar product. These will definitely last a few days, more likely years.

Higher priced hammocks like Ticket to the Moon are a little nicer, have better bags, last longer, and aren’t made in sweat shops.

The cheaper hammocks tend to be a little smaller. But if it’s one person hanging out, it’s fine. I own about a dozen different hammocks of different price points and use my cheap ones regularly without issue.

If you get the cheap ones, you can try and sell them to the participants of the events. Put out an “adopt a hammock” sign or something.

If you buy at Amazon, you can likely just pack them up again and return them.