What would your passengers think of you when you show up with a fancy aviation headset, and then you hand them over something botched up from a pair of cheap eardefenders and a skype headset, with a few connectors soldered on?
My flying club has a bunch of headsets for (cheap) rent. Works fine.
And about a year ago I was in a situation where I was going to do a short pleasure flight with two passengers, but had no ability to get to these headsets. So they had no headsets at all, I only put up my headset during take-off and landing and had ATC on speaker during the cruise with my headset around my neck. Yes it is noisy and I would not recommend this as a long-term solution but twenty-thirty years ago nobody used headsets and that worked just fine.