I had a similar experience to Hiccup when I tried to sell thousands of as-new novels a couple of years ago. Most weren't accepted by the online buying app and those that were offered around 25p! I gave up and took the whole lot to the charity shops.
I'm trying to get back on the kondo wagon after making some progress a couple of years ago.
Toys are a big source of clutter for me, as I have 2 kids and am a childminder. It's been hard to get rid of things my kids have outgrown as I never know what little ones I'll have in the future and what interests they'll have, plus I've had lots of some types of toy as sometimes I've had 4 or 5 little ones all wanting to play with something, so needed duplicates!
But things are getting beyond cluttered as even though I've slowly been getting rid of toys, of course more come in to replace them.
I'm finding that the toys that are 'too nice to get rid of' which are in storage boxes (to be rotated with toys we have out) may as well be gone, as I never remember they're there and they get buried under other stuff and forgotten. Plus we have less space to play as all the boxes take up physical (and mental) space in the house.
So today I went through a huge box of puppets, some I've sorted into story bags, some I've added to other collections to actually use instead of just store and a few of the best I've put online to sell. And 5 bags of these toys and other stuff I took to the charity shop.
The frustrating part is that you can't even see a tiny space where the stuff has gone. But I'm hoping that if I keep going that eventually it will make a difference...
How's everyone else doing with the decluttering?