Do you ever get an itch to offer buy sterling silver for over a bid by a sponsor?

Getting back to the original post

"I am eyeing a transaction next to me with 835 Sterling objects in great condition. The dealer was offering 40% of retail ($408), and I sure wanted to add 50% more (60% of retail) just to get started on a bid."

I really do not understand it all that well. As a silver accumulator myself, I would have stepped in if no deal was concluded and taken a look at the items.
I would have bought them if the asking price was less than the metal value by only a modest amount. I have no idea what the reference to 'retail' means in this context.
I would have considered paying over melt if the items were notably appealing to me because this is often a way to get some really nice stuff for very little money, if you consider the metal value element as not spent but merely invested. I have a lot of pieces of silver around the house that cost a fair amount of cash but are things I could reluctantly turn back into cash in a couple of hours if needed.

OP, do not take some criticism of your terms as attacks. Many people posting try to be precise and specific in descriptions and I think they are helping others do the same, not attacking them.

 

Japan is a small part of Asia. The Middle East, Central, South and Southeast Asia, have all used silver of the 800-900 range at some stage, or still do.
The Middle East and Central Asia were the main buyers of MTT silver, which is .833.
A pendant from Yemen, made of MTT silver, and with a central Maria Theresia Taler for status:

 

For those wondering, MTTs were used as a medium of exchange all over the Middle East for centuries up until the First World War. I've even found one on this side of the Atlantic.

 

STELLA A A A !!!! ... Joy.

 

Coin-silver in the US was made before the days of standard testing, so it could have a range of silver percentage in it. There were really no guarantees. A lot of it was literally made from melting down actual coins or old damaged or out of fashion silverware. Most Spanish silver coins (the predominant silver coin used in Colonial US) was about 90% silver, but there were also European coins at a lower percentage and English at a higher percentage. I have actually tested some of the antique US coin-silver I've collected to figure out the specific gravity, and have found a range indicating somewhat below 80% to above 90%.

 

Hey Doc, I really didn't understand your question at first which is why I didn't respond. I think I now understand that you were asking what I would do if I saw another person negotiating to purchase something that I liked and thought was worth the asking price even though that person was trying to talk the seller down.

I have been in that position, and I don't think I have ever stepped in with a higher offer, tempting though it may be. I wait to see if the negotiation concludes, and only if it doesn't and the buyer steps away will I step in. I think it would be similar (thought clearly to a lesser degree) to grabbing something out of someone else's hand who is holding it in a thrift store. You can't buy everything, and there is always more stuff out there to buy, so let the early bird get his worm, and you'll be in that position yourself someday.