I also find that holding to a price on an item helps the bottom line... but of course there are exceptions.
When I find a super good, bright orange, like-new extension cord (as an example) I put tie-wraps on it and a nice (computer printed) 3 x 5 index card that says, 100 feet, xx gauge (if I know it) and the price...I get $12 for one like that. ALSO ON THE TAG, I say, "no less" and for the hispanic audience in my area..."NO MENOS".
This gets it put back down maybe 2 or 3 times out of 4, but someone always buys it. It may have to go out to the flea three times, but how much trouble is it to load it back in the truck to make that difference between the $8 someone offers and the $12 I want? Not much trouble and if you multiply that by 3 or 4 (or 10) items, you are starting to look at some money.
ON THE OTHER HAND....I have stuck with a price and regretted it. I had a fancy gold/silver plated bolo tie, brand new with a $60 tag on it and was asking $35. A guy offered me $30 and I turned it down. I carried that in my best aluminum display case for maybe four weeks before another person offered me $25 and I took it. No it didn't cost me much in effort and I made almost as much as I would have if I had sold it the first time, so not a biggie, but I did have to show it a few times without selling it, and I did turn down some $18 and $20 offers !
I guess there is not as much demand for a bolo tie as there is for an extension cord, so that was part of the difference.
I have a friend who is just the opposite and prices everything CHEAP and doesn't want to take anything home, but neither of us has been able to convince the other that HIS method is the best. When you come right down to it, whatever WORKS FOR YOU is the best solution. If you can handle any regrets (or satisfactions) you have one way or the other, THAT'S the answer.