I think it's weird to remove the price. After all, that was the ASKING price.
If the buyer and seller reached another arrangement, that's their business. The asking price was up there publicly, why does it suddenly become 'private'? Totally mysterious logic to me.
If I make a knife for a buddy and sell it to him at a discount, it's not going up on the forum with a price anyway.
I've only posted a few for sale here so far, but as a rule, I'd only ask a price I'd be satisfied to get for the knife from any buyer, with no misgivings. I.e. If my best friend insisted on paying my 'retail' price after being offered a discount, I wouldn't feel I'd cheated him, or would I worry he'd feel he'd been had.
I have no qualms about letting anyone know what I was asking publicly for a particular piece at a particular time. Anybody who can't read timestamps and has no understanding of changing market conditions, improved quality, developing reputation etc. probably isn't a knowledgeable customer anyway. Pricing for craftsmanship is a complex equation. If someone wants to argue with your asking prices as if you're a high-volume manufacturer, maybe you don't want to sell to them anyway. If someone remove the price because they think they can do much better next time for the same piece if the buyer is uninformed, that would leave a sour taste in my mouth. Discovering the market price balance is part of the cost of doing business.
OTOH, perhaps I have the luxury of being retentive about this because it's not my full-time job.
My $0.02. There have been spirited discussions around the house on this topic recently.
-Daizee