Hello, and welcome.
You've made an excellent choice to look into the Amiga. Truth be told, though, getting into the Amiga as a non-hobby machine right now is a bit difficult. Hardware is fairly difficult to come by, expensive, and will usually require a bit of user-maintainance to get operating nicely.
Things to be aware of:
-clock batteries in older Amigas may be leaking; this can damage the motherboard so make sure the battery is removed or recently replaced before committing to a purchase
-if you're intending the Amiga as a full PC/Mac replacement, you'll definitely need 3.1 ROMs, at least a 68040 processor, 32MB of RAM, ethernet card, and a retargetable graphics card (the Picasso and Cybervision line are quite good)
-Only the Amiga 3000 can be directly connected to a standard PC monitor. Others will require a television & 520 adaptor, Amiga monitor, or scandoubler.
-Hard drives larger than 4GB are a bit fussy. You'll need some software patches to get them working properly. AmigaOS3.9 deals with this transparently, and is highly recommended if you're new to the platform.
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Aminet is your friend for software
-The Amiga is severely lacking in up-to-date web browsing software, and is rather weak in Wordprocessing and spreadsheet programs. Presentation software and DTP software is very good on the Amiga.
-The Amiga doesn't handle modern media formats very well.
-90% of Amiga support is community-based. We don't have much commercial help these days.
I do think you'll be a little disappointed switching completely to the Amiga, compared to what you're probably used to as an OSX user. I've used one since I was a kid and I can't bear to switch to something else because I love its interface, system structure, responsiveness, and manual control capabilities. It is my primary machine, but I find that there are things I can't do. I'd strongly suggest buying
Amiga Forever and setting up an emulation environment on your Mac. It's a good way to try out the system to see if you like it, with a very minimal investment.
Again, welcome. Best of luck in these troubling times with your medical expenses. Feel free to ask if you need any more info.