Thinking of returning/ Non Recurring subscription?

[Niwashi]

looks like my best option is to buy $20 worth of crysta and use the excess for something else.

You don't need to buy excess. There are a minimum and maximum amount you can buy at a time, and SE will suggest a few round numbers in between, but there is also an option to specify the exact amount you want to buy. As long as it's between the minimum and maximum, you can buy that amount. If you want one month's worth, buy 1299 or 1499 (depending on whether you plan to get entry or standard sub).