In the case of scout assigned to examine a barn find how long is info privileged?

I used to look for old ferraris in the '80s. On occasion I would find one and make a report to the potential buyer (who was providing the lead info on where the car was) but he would not always decide whether to make a bid on it.

I am trying to see what most people think is the ethical way to go (yeah, ethics in used cars, doesn't seem possible, does it!) but let's say I am in Los Angeles and he sends me to look at a car within 100 miles and pays for the gas and film and hey maybe a hamburger along the way. But then after I send him the pictures he never decides, never gets back to me on that particular find. Meanwhile the car is a genuine barn find V12 and going up in value.

I think the proper way to go is for the scout to say before he takes the assignment: "If you don't buy it in one year (0r whatever time limit you want), let me find another customer."
On the other hand, some might say: "No, he who is paying the expenses owns the info and is the ultimate decider on what happens to the information." I think in non-car situations this is true, if someone hires a private detective to check out somebody and assemble a dossier on them, it it's the client who decides what to do with the info, maybe nothing. But the detective can't go shopping the info around as it is privileged info.
One other angle is, if the scout finds a lead on a car on his own, I think he then has more control over the ultimate dissemination of the info and can rightfully impose a deadline on exclusivity, saying something to the client like: "I found this
275/250-whatever and I'll hold it exclusive to you if you want me to go out and inspect it, but if you can't let me know your decision in one week/month/etc. I will then feel free to shop it around."
Does anybody else have experience in sending out a scout--guidelines they have laid down as to what happens to the info if they pass on a car that their scout found?

 

So for example I find a barn find and the potential buyer commissions me to go there at his expense and
photograph it and find the price, it's still "mine" to offer to someone else if the potential buiyer who has paid the expenses rejects it (granted he could have some months to decide) But if he is the one who sent me the lead, the info gained on this foray is his forever unless he deigns to release it. Does that sound hunky dory?
(I'd like to see you explain hunky dory to a foreigner...)