Inquiry: Mortgage Interest Rate with Point Buy Down

[Adonis Williams]

Hey all - 

I am looking to purchase at my 4th property  here in Maryland and I  want to ask lenders what are the lowest interest rates they are seeing for clients who are buying down their rates by 3 points? I see the base interest rate for federal lending is 4.25%–4.50%. Technically, you can't buy a (mortgage) loan interest rate below the federal funds rate right ?  I am curious to know what is the lowest I can expect interest rate to be + buy down with an excellent credit score. Thank you everyone.