I have a KD-3070. If I remember correctly I paid $120 for it. Cosmetics were very good. The cartridge was a Stanton 500 something with a bent loose cantilever, and for some reason the owner had replaced the RCA plugs and not very well, so I had to replace them. Auto-return didn't work which I think is a common problem for these and a simple fix. With a new cartridge (AT95E) it sounds very good. I lived without the auto-return working until I figured out how to fix it. (I have a thread about the fix somewhere on vinylengine - yes here -
https://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=69561 ). After getting everything addressed it runs very well, steady speed, sounds very good.
The KD-3070 is better than the new AT-LP120 I had previously purchased. Since then I have acquired a Pioneer PL-530. Very similar sound to the KD-3070 to my ears, I just prefer the looks of the Pioneer PL-530.
Since my KD-3070 essentially came without a working cartridge, and the RCA plugs needed attention as well as the auto-return I paid a little more than half of what you're looking at. So for you, as others have commented, it comes down to what cartridge is on it and condition vs. the Pioneer PL-518.