This question comes up a lot around here. I am 100% of the opinion a rabbit needs a rabbit companion. I do know some rabbits are perfectly fine by themselves, but they are also in the minority.
Rabbits are fundamentally social creatures. I have to say, even some of the most devoted bun parents would struggle to compete with ability of another rabbit to make the 1st bun happy.
When you go to sleep, work, study, go out socially, go out shopping,shower etc etc this is all cumulative time where your rabbit is alone. This can be in excess of 20 hours of peoples days, leaving the rabbit with a meager 4 hours of actual time with someone.
In pairs rabbits are able to be constantly in contact with one another. Grooming each other frequently and basically just hanging out together.
Bonding is a stressful and often tedious ordeal that most people dont like -it should be the decider in whether you get another rabbit tbh. I had one bond that took about a week, and the other took over 3 months. If you have a shelter that can help you with it, it would be worth looking into!
Like tobyluv says-there is a chance the bond wont work, and then you either end up with 2 seperate rabbits, or someone goes back to the shelter.
As for cost- I honestly didnt notice a huge difference from one rabbit to 2. My first rabbit was such a brat he’d waste a lot of hay anyway, litter got used at the same rate to be honest(as i already cleaned it every 2 days) and then vets fees actually went down as my female cleared up the males eye infections, and was rarely sick
I do have a very serious issue with the increase of fur though..
Personally, I believe all rabbits should be given a chance at having a companion; that could be in the form of bunny dates to see how he interacts with a potential future partner, or in actually attempting to bond them.