I would drop Facebook in a heartbeat but Facebook Marketplace is a strong pull for getting bargains in my local area.
I have alternatives like eBay and Gumtree but they have their own shortcomings.
Examples from Facebook:
- Antique lumber planks 50p a plank
- 4 sticks of DDR4 16GB SODIMMs, £60
- Garden tools, £10
This stuff would be slower and more expensive on eBay, and Gumtree is more of a waiting game as its userbase has definitely shrunk.