A 3 month subscription to Xbox Live Gold is $9.99 through the microsoft store. In order to add more than 3 months to your account, you will need to "manage" your subscription and turn off recurring billing, so you can buy it again for $9.99.
I used this after converting from hot deal earlier today. So it cost 8000 points for 3 month, which isn’t the best i’ve seen, but it is the best conversion I have seen in a while.
https://www.microsoft.c
https://www.microsoft.c