I always advice new comers to fill out their gear lists by buying good, used gear.
What successes have you had at the local thrift sores?

I am going way back for this one - Army surplus Mountain cook set (two nesting 2 qt pots w/ frying pan lid) -still in service 50 years later

Also Army surplus bear paw snowshoes - price $7.50. Worked great right

As a young student, i haunted surplus stores and got a lot of items that worked, some adequately, some extremely well. Thrift stores still have bargains, but you have to know your stuff.

Actually, most of my sores have been pretty expensive.

Found a nice down camping blanket.

Thrift shops have been very good to me over the years. The charity shops are by far the best, although Value Village has established itself here (a more expensive, for-profit chain).

The trick is to walk through regularly. To be efficient with time and gas, I have a "trapline" of errands in different areas, and a quick tour through the local thrift shops is SOP. (I also think it's cheap entertainment, though some consider that weird.)

I have found good US-made folders (Buck 110, Gerber Gator, original Schrade), a Grohmann boat knife, Swedish filleting knives, assorted SAKs in great condition, and even the occasional multitool.

There's car-camping gear too, like Coleman stoves and lightweight pots. Campfire guitars, too, needing only minor repairs.

For those who suffer the misconception that these stores are intended for poor people only, ask the managers: they will tell you that the world is drowning in "stuff" and they are converting it back into cash for programs that truly help those trying to escape poverty and addiction. (While incidentally keeping perfectly good stuff out of the landfills.)

I have found some bargains in UK charity shops, but it sounds as though the USA stores may carry a better selection.
Many UK charities are anti-knife and wont sell multi tools or SAKs and the like. And even if the charity has no such policy, individual staff might.
There is also a general reluctance to handle "hazardous" goods including camp stoves or fuel burning lanterns.

I have obtained several pocket knives and multi tools "via the back door" of a local charity shop. I know well one of the volunteers at the shop and they save for me certain prohibited items that would never appear in the shop.

Aha! You have cracked the code. The keyword is "trust." If the volunteers know you and trust that you aren't bent on mayhem, an arrangement can be made. They don't want these items sent to a landfill; they don't want them as street weapons either. Chat them up, be a regular donor of things they can sell, and always donate a few dollars when they provide you with items they can't put on the shelves. It works.

People skills

Agreed, people skills; and building positive community connections.

I would add: work on positive interactions with the store manager. When there's a policy in place, volunteers and front-line staff often don't have the authority to make these kinds of grey-area decisions. The manager has some latitude to make judgement calls.

Yes, be nice, introduce yourself.
Let them know what you are looking for.
(Bring in donations)

Just picked up a hammock quilt...for $10