ARC, it sounds like your space is a pretty hard constraint - that's simply reality. Absolutely, put everything you can on wheels. I was seriously space constrained for many years. We finally added on a nice sized work shop. My main machines are set on the floor, but everything I can I get wheels under it, or sits on purpose built blocks. I also have a pallet jack which is super handy - the equipment that is on blocks is very easy to move. The point being that if you have a good arrangement to move things, then you can work with more items in that space.
There is nothing wrong with paying "gold plated" prices, so long as you get a machine that is likewise really super nice. Everyone dreams of getting the gold plated machine for super cheap. Yes, it does happen, but it is sort of like winning a lottery - it happens, but don't count on it. I picked up several "screaming good, you suck" deals - however, none of them looked like it at the time (they started out looking horrible). The first machine I got, I paid the "gold plated price" for a used (just slightly used, but not brand new) very nice lathe.
In retrospect, paying the money and getting into a good machine off the bat, turned out very well. I went through all the same agony (actually it was a lot of fun) of ordering catalogs, getting machining books, talking to machinists, looking at machines etc for about 3 years. I kept saving up money - and finally went ahead and spent the cash. For the lathe, the power, the transport and the first round of basic tooling it was about $16,000 - and that was in 1983. Your situation is different, you are much more knowledgeable about machining and you have access to machines - I had neither of those when I started.
I do not agree that since this is a hobby, the machine has to be cheap. All in I have about $30,000 into 10 machines (depending on what you define as a real machine) - I know plenty of folks who have more than that in a boat, RV, sleds, truck, . . . hobbies which cost more and are used less than the hobby I am into. Spending $5000 for a decent little machine gets a person going (sounds like you know machines - $5K is still cheap, and all the machines you have mentioned are bottom end - even brand new there is nothing gold plated about them at all). If you start with a decent machine, it will always be useful - even when / if you get more machines. That first lathe that I bought back in 1983 is still a very useful part of my kit (I now have lots more iron, but that first lathe is my go to machine).
I suggest you pass on the mentioned CL machine and look for a more competent machine (while saving some funds, get your transport lined up, think about your work space and power), and be ready to move fast.