With regards to companies, I think pg's answer is the correct one.
In real estate, there is an institution called "earnest money." It is structurally similar to your 2nd bullet point -- a deposit against the eventual transaction price which is forfeited if the prospective buyer doesn't close the transaction within a particular window of time. (It gets returned if the seller kills the deal.) Earnest money protects the interests of the potential seller by screening out bozos. It protects the interests of the potential buyer by reassuring the potential seller that there are 120,000 reasons attesting to the buyer being really serious about the $6 million commercial property acquisition being discussed and therefore questions about e.g. engineering, permits, tenants, etc should be responded to as quickly as feasible.
$50,000 is barely about two work-weeks or less at the rates involved of professionals involve in M&A. If you want a quick out from fishing expeditions, tell them that you're willing to entertain offers but that, to avoid wasting the business' legal/accounting/engineering resources, you'll require $50k earnest money prior to dedicating them to exploring the feasibility of a deal.
A related strategy: "I'm not super-interested in doing an investment / acquisition / etc at the moment, but I'm a reasonable businessman and willing to entertain your offer." "We need a $FOO to get the ball rolling." "I have entertained that offer and do not feel it is the best use of our time to proceed on this at this time." "It is absolutely standard to..." "If your firm really wants to do this, I'm sure you'll figure out a way to make it happen. If not, no worries -- we'll both end this chat no worse than where we started it. Best of luck in your endeavors."
In real estate, there is an institution called "earnest money." It is structurally similar to your 2nd bullet point -- a deposit against the eventual transaction price which is forfeited if the prospective buyer doesn't close the transaction within a particular window of time. (It gets returned if the seller kills the deal.) Earnest money protects the interests of the potential seller by screening out bozos. It protects the interests of the potential buyer by reassuring the potential seller that there are 120,000 reasons attesting to the buyer being really serious about the $6 million commercial property acquisition being discussed and therefore questions about e.g. engineering, permits, tenants, etc should be responded to as quickly as feasible.
$50,000 is barely about two work-weeks or less at the rates involved of professionals involve in M&A. If you want a quick out from fishing expeditions, tell them that you're willing to entertain offers but that, to avoid wasting the business' legal/accounting/engineering resources, you'll require $50k earnest money prior to dedicating them to exploring the feasibility of a deal.
A related strategy: "I'm not super-interested in doing an investment / acquisition / etc at the moment, but I'm a reasonable businessman and willing to entertain your offer." "We need a $FOO to get the ball rolling." "I have entertained that offer and do not feel it is the best use of our time to proceed on this at this time." "It is absolutely standard to..." "If your firm really wants to do this, I'm sure you'll figure out a way to make it happen. If not, no worries -- we'll both end this chat no worse than where we started it. Best of luck in your endeavors."