I have 4 bunnies and they dont cost that much to feed and water.. I give them dry food, water and hay every day, you can use meadow hay or something similar.. I give them veggies every few days, these include carrots, cabbage in moderation, curly kale, sweetcorn, brussell sprouts, broccolli, swede and anything else that you think they may like.. Apples, pears and strawberries are also liked by some bunnies.. I dont give mine all those at one time, I alternate what veggies they have.. I estimate that my 4 cost less than £20 ($35) per month and that includes their litter pellets too..
Remember the added expense of vet bills and if you choose to have them vaccinated each year that costs too.. Mine have all been spayed/neutered as I feel that it makes a happier pet.. Also females who do not breed are at a higher risk of getting cancer of the reproductive system, so that is another thing to consider..
Keep us informed of what you choose to do..