You may have success reaching out to hello@wanikani.com and making a case for a discount coupon, but your best bet is usually to get an annual subscription (if you can afford it) and then take advantage of the annual lifetime sale in December. If you have an annual subscription, you get the value of any remaining months subtracted from the lifetime purchase price and so that’s the way to get the best value for money, in general.
Oh and while I’m here…
\textcolor{pink}{\huge \textsf{WELCOME! ^-^}}
Take the time to check out the FAQ and GUIDE if you haven’t already.
There’s also a lot of good stuff on the forum to help you, like:
The Ultimate Guide for WK
The Ultimate Additional Japanese Resource List
The New and Improved List of API and Third-Party Apps
I hope your Japanese learning journey goes well and that you enjoy your time with us on the forums.