Since you are talking about a residential property, temporary rate buydown loans are an options. They are a little different from buying down your rate at the for the duration of your loan like you can with other loans. These loans help your buy down your rate temporarily for 1-3 years usually, with rates reverting to market rate from the time the loan was closed.
If you want a much lower rate than market rates right now and you have a lot more money for downpayment and closing costs, temporary rate buy down loans that allow you with a buy down your rate to lower your rate significantly for a couple of years with rates increasing back after the temporary rate buydown period(usually 1-3 years; dependent on lender).Not all lenders do this loan product. This is a little different than buying down your rate with other loan products for the full loan duration. This allows you to much more significantly buy down your rate but for a few years. You could refinance when rates are lower in a couple of years. I don't know however if those loans are allowed for self employed borrowers though