They made enough of them that it's not impossible to find one, unlike the first two that are damn near impossible to find. There are other linear models too, the entry model PS-LX520 for instance is quite easy to find for sale and quite inexpensive, but it's nothing like a TOTL model like the other ones I listed - works ok but nothing to get excited over.
Don't overlook the PS-X50/60/70 units. They are real sleepers and sound fantastic easily competing with many so called value audiophile tables, ie Rega.
http://www.thevintageknob.org/sony-PS-X70.html
The bearings on the PUA-7 are incredibly low drag, a whisp of breath with the antiskate off will easily move the zero balanced arm in both axis.