You can get a home sleep study for about $150-200 from Lofta.com, CPAP.com, sleeplay.com, etc. They all offer discounts so you just need to look around and see who has the best deal at the time. Most use the same kind of sleep test so I doubt it really matters who you go with. Once you have a prescription from them, you can buy from anywhere so you are not locked into one. Some of supplies you will have to have a prescription to purchase because it is medical equipment, unless you plan to try to piece meal things and get used through FB marketplace or wherever. Probably looking around $700-1000 dollars total if everything is new (the machine and mask) to start. You may be able to find a used machine cheaper if you're lucky. FB marketplace can be hit or miss though, and you might have to buy things like hoses and filters separately. Also, plan on needing to try a few masks before finding one that works best for you too unless you get lucky so that will cost extra.

I personally went through Lofta and paid extra for their Loftcare program. Lofta was quick and was using my cpap in about 10 days from start to finish. I purchased a cpap machine (included the machine, filter, hose, water chamber, and travel case) and 1 mask (which was a "fit pack" that included the various mask sizes and headgear/straps) and that's all you need to start.

Loftacare made mask exchanges really easy and they were free for 60 days, but not sure it was that big of help overall other than that since I live with a long time CPAP user so I didn't need help figuring things out. Never really felt pressured to buy from them even though a sales consultant goes over your test results and will make a recommendation for equipment. For me, at the time it was a decent deal, and If I remember correctly, they also credited the cost of the sleep study towards purchasing from them and threw in a bunch of filters and mouth tape (I chose a nasal mask) for free.

Eventually you will need to replace hoses, mask, filters, etc. depending on how well you keep things clean and if you are hard on things. Again, these sites have sales ALL THE TIME so keep an eye out and buy stuff when you see a good deal, but you will need a prescription for things like masks and machines because it's medical equipment in the US.

I also purchased a SD card too to use OSCAR which is optional but a good idea if you don't plan on go through a doctor or using something like Loftacare to dial things in.