You could upgrade the motor, to a stronger one. I have upgraded the mini mill motor to a 600W for very cheap.
https://www.youtube.com/watch?v=ndhsCeuEv-4I did the motor mount in a much easier way, just adding some small aluminum blocs to support it.
I added the emergency stop as well, but to tell you the truth, I never use it.
It looks like that allelectronics place is not in business anymore.
Also I have added the Littlemachineshop.com pulley system, making it much quieter and smoother running.
Added an RPM readout, that is a few bucks.
Also added a digital readout(DRO) for all three axis, not expensive either.
About the lathe, I have picked up a new Ebay 8.9"x23.6" 1000W brushless lathe, for around $1000, after some discount, because had some issues.
I don't recommend them at all, unless you rebuild it from the get go. Both ways(X axis) are not parallel, they are off a few thousands from each other at opposite sides.
I had to use a sand paper on a block, and I had to sand off the excess material at the bottom of the ways(for quite a long time), which are not even smooth(!). It is still not perfect, but it is usable.
The tailstock bore it was unusable, the hole it was machined from both sides and they were not concentric to each other. I had to bore it out and make a bronze insert sleave to fix it. I'm lucky, because I could do all of this at my workplace. Otherwise I would have been screwed badly.
Watch a few videos on Youtube about this. I remember there is an Australian Youtuber, who is very good in explaining how he fixed his machine.
It needs a lot of reworking/shimming to be acceptable. Parting off is almost impossible, it rattles like hell. I'm using a .063" parting tool, and even that one rattles.
I know that is tempting to get a new lathe, but I don't recommend them at all. The harbor Freight one, is way to small for anything imho.
To have something decent, I would recommend Precision Matthews machines, but they are more expensive, I believe Grizzly has some similar ones as well. The guy is on machining forums as well.
With older used machines, it is tricky, because they could be worn out after all these years of use, or rusted. There is no easy way to tell, if they are still in good working condition, you would need test indicators to take some measurements, to be sure. You could move the saddle at both ends, to see, if they are much tighter there, than at the area where it is mostly used. If there is a big difference, then move on. Same goes with a mill. It means, that in that area is a dip in the ways and it needs redone.
I also added DRO to my mini lathe, a separate DRO for the tailstock, made out of a digital caliper. Used a worktable 1.5" thick butcher block style top (free from work), and cut it to my toolchest size and placed the lathe on top of it. Also added some scrap Aluminum blocks from work, to raise it a bit for easier cleaning in the pan. A bit to high overall, but usable.
I can actually cut decent cuts with it, in steel. Even .100" cuts. I swapped the tool holder with a wedge lock style one(the only style that I would recommend in this price range), found it cheap on Ebay, sold by a university slightly used. I get my tool holders from Amazon. Accusize brand is very nice for the money.