I've got two pieces I've had for quite some time, and still use them fairly often.

31 years: Yamaha CS-01 Analog Monophonic Mini Synthesizer (with breath controller)...also have the matching mixer and headphone amp that came with it.

25 years: Yamaha TQ-5 FM Tone generator (with built in effects and sequencer).

Both instruments still work and look as new...had cases built for them.

I guess I should add my two Yamaha MS-60S powered 60-watt monitors, that are roughly 25 years old...still use them daily on my Tyros4, and they still sound and look as new (had cases made for them, too).

I suspect I will have my Tyros4 for quite some time...it has all I need.

Ian

PS...probably not relevant, but I still have my late Mum's well over 200 year old Ruggeri violin here with me, although I've never really learned how to play it very well. It's in incredibly fine condition and is in it's original case with original horse-hair bow. I've had it over 50 years.