Bargain about prices

Is it OK to bargain about prices in outdoor markets, flea markets, stalls, etc. Is there a difference in doing this between doing this in larger cities and small/rural villages. If yes, is there a particular etiquette to doing so.

Thanks.

- Flea markets (where people bring in their used clothing, etc.): OK

- Farmers markets (where local, small-scale honest farmers bring in their fresh produce): I'd say not really, as they often come offer their products at rock-bottom prices to begin with. If you buy a LOT, the seller might offer you a discount.

- Bargaining is often "enjoyed" by Osaka people. But that involves a lot of friendly chatting, as a result of which they might agree with a discount in the end, but that's true in any place where bargaining is done, I guess :)