I spent around £8-10 for five animals - three rabbits (1.5-2 cups of veg per day each) and two piggies (one cup per day each) but as the rabbits have a little more veg per day than the piggies do, so by the time that’s taken into account what I buy probably would go round six or seven piggies.
i buy a couple of cucumbers, four peppers (Although some of that is also eaten by the people in the house!), 2/3 packs of coriander, two packs of little gem lettuce, a bag of spring greens, a pack of green beans. Something the odd extra thing but the items ive listed form the basis.
I feed half in the morning and half in the evening.
I'm the same as Yvonne though, they spend a lot of time on grass in summer so tend to get a little less veg (not drastically less), plus I grow my own so the cost is less in summer