I mix one 350g bag £1.99 into 2.5kg approx of Chudleys Rabbit Royale and that lasts me approx 1 week to 10 days for 4 - a 15kg bag of Chudleys is £15.00 inc delivery.
I feed a bowl each the size of their head per day. Most mornings I probably throw a quarter away at least as it isn't always finished, I don't like to leave it till it's gone, they get fresh. Works for me but, mine are more greedy over hay and greens than dried food. I buy meadow, Oat wheat & Barley, Oat hay and sometimes readigrass, they get fresh meadow and either Oat Wheat and Barley or Oat or a mixture to fill their baskets, fresh meadow in the litter trays. My rabbits don't tend to overeat as I've read they can have a tendancy to do, I think because they are quite active and mentally stimulated.:wave: