As you already mentioned, cost is one of the major factors to consider whether you should have one bun or a pair. When you have two buns, everything doubles – vet care, food etc. You need to ask yourself (or your parents if they are the financial providers) whether you can afford to house two. Personally my husband and I have decided to get one bun only as that’s what we can afford at the moment, although we would love to get him a friend when we have the budget eventually.
In terms of boredom, you can make up for it by giving the bun lots of toys to play with or things to do. There are many DIY ideas available out there for reference and these are fairly inexpensive.
As for chewing…a lot of bunnies chew regardless of whether they have a friend or not. You can give the bun chewable toys (e.g willow ball) for that.
Since you’ve never owned a rabbit, I’d say it’s safe to start with just one so that you understand the commitments that come along with it. It’s better than having two at once and be overwhelmed once you realise they are not the easiest animals to care for (despite their cuteness).