We have been living like this for some time, since DTwins arrival, and (not sounding like a dickhead) but not through necessity, but the almost buzz of a feeling to know we are saving so much, being better for the planet and putting money back into the hands of either charities or fellow locals.
I was a terrible hoarder. Now, if we haven't used it in two years, it goes on FB. Likewise anything bulky of the kids. Old cooking stuff, books. The house is looking so much better, like it can breathe again. And it's nice having the small, but steady cash inflow.
I buy nearly all DC clothes from FB, charity shop or boot fairs. Bundles are the best. I pick out the bits that fit DD/DS best and put the rest straight on eBay and generally make £20 profit, so the kids are clothed essentially for free and I have £20. I get them both a bundle for around £5-10 nearly every month. We also have a kids clothing charity nearby and I take a lot of the excess there as well.
Toys, both their big presents last year came from FB. A full Sylvanian set up, as new, about £300 worth of stuff, £40. And a huge car garage with linking race track, £25. This year I already have a hotwheels motorised crash arena, complete and boxed from the charity shop for £8.
It's the way forward. It's about value. And often profit.