Thanks for the heads up! I bought 6 x $500 face value.
At first I was thinking, "500 is a lot, I should probably get just 1, not 2." Then I checked my reservations and remembered I have almost $2k of BS/AT tix booked for the next 3 months. With $3k in GCs I can refund those cash tix and rebook with GCs, leaving only around $1k net cash tied up in the remaining GCs.