Another option is to do margin borrowing on some investment assets that you have. Because it is a secured loan the interest rates are much cheaper than credit cards. Schwab has a good set up, it can be configured to automatically do a loan if you withdraw more funds from your checking account than you have. They currently charge about 12% but there are other options around 6%.
My friend used this set up for his emergency fund since he felt like it would be better to earn an investment return and take a loan in an emergency instead of sitting around having your money earn minimal amounts in a checking account.
Yes, borrowing on margin is a really good strategy, although it depends on your broker how that functions. I've had a good experience using this for smaller amounts, but given market volatility I'm concerned about borrowing this large of a sum on margin, as I don't know what clown stuff is going to happen in the next 6 months, a credit card feels lower risk to me, although the interest rate is higher. I actually considered this, using a credit card will cost me $530 in additional interest over taking margin, but has lower risks in my estimation. That $530 is not enough for me to feel it's worth it to do it via a margin loan.
That said, margin is really useful as a tool because it lets you unlock the value of your investments without tax penalties in lower volatility markets.
My friend used this set up for his emergency fund since he felt like it would be better to earn an investment return and take a loan in an emergency instead of sitting around having your money earn minimal amounts in a checking account.