Buying extra supplies

I've seen several posts that say we should keep back up supplies. I'm wondering which items people normally buy backups of, and whether they use insurance to buy the backups. A nonheated hose looks pretty cheap, and I've already got some filters (I'm guessing those are cheap too). On the other hand, while CPAP.com sells the mask I use, it costs $127. So am I right in guessing that folks wait until their insurance will pay for another, and then try to keep a spare on hand?

On a related note: I've seen praise for the Hose Buddy. I'm thinking of buying that and a heated hose converter kit for my machine. Are such things usually covered by insurance, or do insurance companies view them as unnecessary?

I just bought a pack of 50 ultrafine filters from a supplier on Amazon as a stockpile.
Since there is only one mask that works for me, I have a stash of Oracle 2 masks 'cause I worry about them being discontinued. Most folks seem to keep their older masks as backup.

I don't think insurance companies pay for backup machines. I do have one that I got when I was having problems with warranty repair through Lincare, 'nuff said about that.

If you have a good DME, they can provide you with a loaner if you have a maintainance issue on your machine.