Welcome to Apnea Board
I suffered with severe, untreated OSA for many years, which essentially means that i was a zombie before it was fashionable. By 2005, CPAP technology had improved to the point where I could get effective and even comfortable therapy. I've been a hosehead ever since and I've never looked back.
I feel much, much better, but some of what I've lost is gone for good. Long-term sleep deprivation can lead to permanent impairment.
So I'm asking you to please, don't let the admittedly high cost of new CPAP equipment stop you from getting effective therapy as soon as possible.
What this post isn't, though, is a lecture about "what is more important, your rent and other monthly expenses or your health?". I understand that there are folks who qualify for Medicaid or other subsidized healthcare, and other folks who have good healthcare benefits through their employment. But there are a huge number of folks who fall through the cracks, and for them, paying full price for CPAP gear can be a staggering expense.
The most important thing to keep in mind at this point is that there are alternatives to buying brand-new CPAP equipment.
CPAP therapy is relatively common in the U.S. today, and as a result, there is a huge amount of perfectly servicable used equipment out there, most of it just gathering dust. Here are just a few places you can find it:
Online auction sites.
eBay's terms of service do not allow the sale of CPAP machines or even masks, so sellers there are restricted to offering "mask parts". But there are plenty of other sites, most without such restrictions, such as eCrater. Here's a good starting point: 17 Alternatives to eBay in 2013
Your local sleep lab.
Sleep labs often receive donated equipment from a DME supplier whose services they recommend. If you explain your situation, a good sleep lab will do what they can to help you find what you need. They may offer you a surplus unit, or they may be able to put you in touch with a DME rep who has proven to be helpful in the past. Your sleep lab should also have a wide selection of masks for you to try on. That is a very helpful way to learn what style and size of mask is best for you, without having to purchase a number of different masks by trial-and-error.
Your local DME provider.
When I was first working on adjusting to CPAP, I wanted to try machines from "The Big Three" (Respironics, Puritan Bennett, and ResMed, at the time). My DME rep said, "no problem", and brought me one of each. When I decided on the ResMed, he told me, "I'll have to take the Respironics back, because that was a special order, but the Puritan Bennett, you can keep." When I protested that I didn't need it, he said, "Keep it as a spare. That's our most popular machine, I have used ones stacked to the rafters in our warehouse, and we don't sell 'em."
Your local Lung Association.
In some parts of the country, the Lung Association administers or facilitates support groups for CPAP patients, some of which include equipment exchange or donation pools.
CPAP machines are ubitquitous enough where they're starting to turn up in quantity at estate sales and pawn shops. Typically they'll sell for pennies on the dollar.
Local "Bargain Hunter" publications or websites.
Here in Connecticut, there's a newspaper called "The Bargain News". They've been around for at least 40 years that I know of, and they have an online presence as well. Anyplace where you can find listings of secondhand household merchandise for sale is likely to have a CPAP machine or two on offer. Again, usually for pennies on the dollar. An excellent option would be to place a "wanted" ad. You might be surprised at the response you get.
Any facility that offers unclaimed luggage for sale will undoubtedly have CPAP units too. And they're easy to spot, most of them will be in neat, custom-sized nylon luggage with the manufacturer's logo prominently displayed.
There's more, but I think I've given you a good starting point.
With any used machine, you'll need a new filter. Provided that it is properly-fitted, a used mask can be easily cleaned, disinfected, and re-used. You can clean a used hose, but they're cheap enough (<$10) where I don't think I'd bother. If you take your prescription (I'm assuming you have one since you've posted a pressure in your profile) and your newly-acquired CPAP to your local DME, they should be willing to set it and test it's operation for you for a modest fee. Alternately, you can come here for advice...that's what a support group is for!
Obviously, a brand-new machine from an authorized DME provider is the gold standard. But hopefully, there are those of of us who remember what it's like to live with untreated OSA and are willing to do what we can to help you on your way.
Good luck! Carl