Honestly I just use water if I don't have wine, if you are doing a eucharistic rite i.e. energy is being called down into the food and drink, water works just fine as does any food. One could even use bread or indeed anything.
The same goes for wine in general, most rituals call for red and I can't stand the taste. My spirits don't seem to care that I only like Pinot Grigio and can only afford a cheap brand!