Several pieces from my Ghostbusters cosplay/prop replica collections have gotten rather more casual use than I expected.
One time we were under bad weather and told to seek shelter, so we had the kids in the bathtub under a blanket. As an afterthought, I realized I owned enough real hardhats for cosplay purposes to distribute one to each of us. I personally wore the one to which I'd attached the battery-operated headlamp.
I've also used that hardhat when changing lightbulbs in the windowless laundry room, so I can illuminate where I'm looking and have both hands free.
One time our power was out for several hours, and thus our cordless phones were inoperable, and the cell phones couldn't be recharged, so I took my giant 'Ray Stantz' Maglite normally used on my web belt, and went digging through some boxes until I found one of the plug-into-the-wall phones I'd collected and used that to call the power company.
I bought an Optivisor just because Sigourney Weaver wears one in GB2. Now that I need bifocals, it came in handy for some wiring and soldering projects.
I bought a coat very similar to Dan Aykroyd's in the opening library scenes of the first film. It's an English coat, wool and very warm, and became my favorite winter coat.
Which reminds me... I also bought a vintage Nikon camera case like he wears in those scenes.
This item arrived and I realized it was a perfect fit around my modern Sony camera, so I decided to get constant use out of it.
Two days later, coming back from a children's birthday party in October 2015, we had a bad wreck and were tossed around inside my buddy Brandon's aptly-named Avalanche as it rolled in the median. We all had minor bumps and bruises, but we were mainly okay, which was miraculous considering how violent it was. My eyeglasses were thrown off my head and wound up in the backseat with my son Zak, the camera was flung off my neck and wound up elsewhere in the cab, an external plastic case for the flash attachment was cracked and shattered... but the camera inside the 30-year-old hard leather case was perfectly fine... and was immediately used to take all of the photos and video for insurance purposes.
https://youtu.be/CtFRWv-U3aY?t=1m39s
In fact, the Nikon case got so much more use from me since 2015 that I eventually bought another for cosplay/prop use only, and keep the one that's beginning to look a bit worn just for real-life camera protection.
And the most recent instance of everyday prop usage was this pair of headphones that I bought to make Egon's Walkman/stethoscope from GB1. They were so pristine-- even including the foam covers-- that I couldn't bring myself to cut the wires just yet.
I awoke one morning to find them on my wife's nightstand, plugged into her tablet. She'd pressed them into service after I'd fallen asleep, unaware they were 35 years old and intended for cosplay.
Alex
EDIT: I had originally lumped these two Janine phones in with the pics of the Dana 'donut' phone. But it occurred to me later that I've never been able to test either of those due to their larger 'multi-line' office plugs, so I removed the pic. The thumbnail remains below.