Can I ask a prospective buyer to prove they actually have the funds before I take them seriously?

Yes, and it's standard, sensible practice before you share sensitive financial information or spend real time with a prospective buyer. There's no legal rule requiring you to engage seriously with every inquiry, and asking for evidence of available funds or financing capacity — a bank or investment statement, a pre-approval letter, or a clear explanation of how the purchase would be financed — is a reasonable screening step, not something a genuine buyer should be offended by.

How much detail to require can scale with how far along the conversation is: a casual early inquiry doesn't need the same proof as someone asking for detailed financial statements or wanting to make a formal offer. Buyers who resist any verification at all, or who get evasive when asked, are giving you useful information about how seriously to treat them. This kind of screening also protects you from spending time and disclosing sensitive details to someone who was never in a position to actually close. A Treadstone business lawyer can help you build proof-of-funds and qualification steps into your process, particularly if you're managing a sale without a broker.