My sleep study cost 10,000, and was inconclusive. I had to get a home study to confirm my apnea (these cannot be used to test CPAP settings though). If you have insurance, it's probably in your best interest to use it.
You could also ask the doctor your insurance question over the phone - many want to help. My instinct is that sleep apnea is so common that insurance companies would lose too many customers if they turned down people with the condition. But of course it can't hurt to check.
Get her help as soon as possible, though. Apnea is dangerous and can cause car accidents, heart issues, and diabetes. Treated early you can totally get your health and life back.
Sleep apnea is a fad now of sleep medical docs. I have severe obstructive sleep apnea and am on CPAP machine. This is a fatal disease. 70% of Alzheimer patients have sleep apnea (sleeping breathing problems). If your wife is diagnosed with sleep apnea by all means get help. CPAP machine may not be necessary. There are a myriad of causes of breathing problems thru out life. This cold winter can cause breathing problems both awake and asleep. Research out breathing problem during sleep; it just may be a stuffed animal for Valentine's Day for her to sleep with will have her breathing fine again.
P.S. Money is the root of all evil. If you truly love her as a person damn the cost full speed ahead.
Agree with flipper336. Getting more detail on the life insurance issue, though, preferably from an agent who sells for multiple life insurance companies, would be a good idea. Getting life insurance through an employer that has a group life policy is not usually a big deal, but if she needs to have individual life insurance, then maybe you'll want to take care of that before she has the sleep study. Ask your agent all the questions beforehand, and be honest. Insurance companies can deny claims later on, if you lie on an application.
Pre-existing conditions for health insurance don't matter anymore, with the new changes in federal law. You are right that what is most important is your wife's health. It's not just a matter of sleeping better and feeling better. Untreated sleep apnea is associated with a higher-than-normal rate of cardiac events and premature death. Remember Reggie White, the Philadelphia Eagles defensive end who died in his sleep at age 43, not long after he retired from the NFL? He had sleep apnea, and it is thought that the cause of death was a fatal arrhythmia during sleep. Better for your wife to be turned down for life insurance (if it comes to that) and live, than to get a great life insurance policy and then have to use it.
She might not even have sleep apnea, anyway. I mean, maybe you're pretty sure she does, if you've observed things like loud snoring and pauses in her breathing, but if she's having trouble getting enough sleep, she needs the sleep study to find out exactly what is going on. Good luck.
I would have to say no to your questions. I have been diagnosed with Sleep apnea and have been able to get life insurance. Also the only way that I know she would be able to get diagnosed is to have a sleep study done. Sure you can buy a CPAP machine out of pocket but without the sleep study how will a doctor know what kind of setting your wife will need, if she even needs a machine. You can see about paying cash for everything but that will be expensive.