Grefrin: So all that being said, does anyone know if it's possible to buy more than 1600 points at a time?
Not possible, as far as I could figure out.
Grefrin: I'm unclear on whether the coupon is even reusable.
You can. I bought three DLC for ME3 and had to do each transaction separately. The code worked for each one.
Grefrin: Also, any thoughts on the value of the Mass Effect DLC? I know it's been fairly highly rated, but I'm a little reluctant to throw so much money at this. (A little over $50, down from roughly $75 for Arrival, Lair of the Shadow Broker, Overlord, Kasumi, Leviathan, Omega, & Citadel.) Am I being too cheap about this, or should I jump on this deal while I can?
From what I've read and from talking to my daughter about them, these are worth it:
Arrival, Lair of the Shadow Broker, Kasumi.
She thought Overlord was just 'meh'.
These ones I just bought tonight, so have no personal experience with them, nor does my daughter:
Leviathan, Omega, & Citadel.
But from what I've been reading, Omega seems to be regarded as the weakest. The other two seem to be fairly highly regarded. Although make sure you read the description of Citadel, as it doesn't drive the story forward or add anything to it. It seems it's just good fun around the end of the game and was intended by BioWare as more lighthearted fanservice.