Car boots sales would be a good place to start for hand tools of all shapes and sizes, sometimes bigger stuff too but historically they've been rich picking grounds for hand tools (including vices).
Then in no particular order, vintage/steam rallies, Gumtree, eBay of course, Facebook's marketplace, junk shops, charity shops (in some places, not all do tools), recycling centres also in some locations and scrap-metal merchants.
There are indications that car boots have had their day as a source of cheap buys but any sale (or area?) can wax and wane, or have a off day, so only regular visitors will known what the current lay of the land is. And two very recent threads here in Hand Tools have shown that great finds for little money are still very possible. But if you're used to the prices of stuff for vintage cars even 'expensive' tools by the standards of many here probably won't phase you in the slightest!
