The DI needs to stay wet. If it dries out it goes bad. I go through a cartridge of DI about every 12 months. For me, this means getting in bulk won't really work cause I don't have a way to vacuum seal it. If people want to split a bag of DI (I think they have a 5 lb bag that is enough for 4 recharges) I'd be willing to go in on one. I'll be due for a switch in the January time frame. I also will go in on the order for a 6 pack of filters.
Getting a 15% discount on the typhoon with free shipping is a great deal. If all those on this thread that need an RO/DI get in on this (4 so far, I think) and a few of us buy extra filters, I think you'll hit the minimum.