With the exception of a wine pairing at V&A's for our anniversary, and a day at the F&W Festival at Epcot without the kids, I think I can count on one hand the number of drinks we've purchased at WDW, primarily, because the prices are too high. However, we rarely order drinks out at home for the same reason (and because I refuse to drive after drinking even one drink).
Even though the prices are less expensive on
DCL, we find that we still don't drink that much on board. Generally, we only order drinks when we're at the adult pool (a BBC is about $5.00 and the drink of the day is less than $4.00) or when we're on
Castaway Cay (2 for 1 between 1:00 pm and 2:00 pm!!). Plus, there's no tax on the cruise ship! However, we do splurge at the sailaway party and buy a drink for all of us, including the kids. I do it even though I find it outrageous that DCL charges the same for the same drink whether or not they spike it with rum for the adults or virgin for the kids, it's a tradition for us. It's still less expensive than a drink at WDW and you get a "free" souvenir glass.
This fall, we're doing a 20th Anniversary trip to the Board Walk (first time using our
DVC membership!) and a 4-night trip on the Wonder sans kids. We will visit Epcot and I plan to enjoy a Grey Goose Slushie or Grand Marnier Slushie (or both!!)
regardless of price. I've been wanting to try one the last couple of trips, but haven't done so.
I agree that its all simple supply & demand on pricing. At certain price points, we just say no.