I've always felt uneasy about insurance in the sense of what if they don't pay up? that said I rarely hear of people having a problem. The exclusions would have been prohibitive with Mousey who had EC when I adopted her. What I hadn't factored in to the cost of keeping bunnies is their needs when they are older (she has: daily metacam & joint support tablets, regular mite treatment & 'preventative' panacur) - I don't know whether insurance covers these things? Over the last 28 ish years I've had 9 bunnies (incl my current three). I'd say 2 of them I'd have been better to insure. Boo had an 'expensive' couple of years when she had a weird cyst causing all sorts of dental problems but its 15 months since her last. I do think the peace of mind would be nice but I'd have to get over my trust issues to obtain that. I don't know if any of your bunnies are 5+ years. I think that becomes an issue as most won't insure at 5+ but Agria do an age amnesty thing - every October I believe
Joint support would possibly/probably be covered if the vet prescribes it, I've never had a problem with claiming joint support in varying forms for my arthritic dogs. But they wouldn't cover it for prevention. They wouldn't cover mite treatment but would cover panacur, again if prescribed, but not if it as pre-existing.
I have mine insured, £11 a month each, with no pre-existing conditions. I just felt it was too much of a risk with giants, given the likelihood of joint issues in the future. It is fine to put a bit away, but be realisitic - £30 a month is only £360 a year, assuming you don't use any, and if you're looking at a stasis with a couple of days hospitalisation, or any kind of surgery, you'd be way over that in the space of a day. So if you opt for savings, also have a credit card or something in case you need it before you have enough in savings.
I think a lot depends on how many you have, when you get multiple animals it becomes less cost effective, and a better gamble to set aside that money instead. I also think - unsavoury though it is - it is worth thinking about what you are comfortable putting an animal through before you have to. Insurance can often mean more invasive treatment, more prolonged treatment, just because you can and it isn't always in the animal's best interests. Likewise if you wouldn't be willing to put a rabbit through surgery for the most likely things (broken legs, severe stasis perhaps) then insurance might be less appealing.
With my dogs I have always got much more back than I paid in. The bunnies so far are more in than out but I'm happy to keep it that way!!
Insuranceis always a gamble, some you win and some you lose, but if you opt against it make sure you are aware of the true costs, many people aren't sadly, and think about lifechanging decisions ahead of time. You can change your mind of course, but speaking from experience it does really help if you have considered things before you get to crunch time.