Wow, looks like nice copies of both lenses.  I think the 50~135 is the better deal at that price, but based on my (admittedly last-century) experiences with Danish gear prices, those are good deals for someone in the area.

The price for a nice 75-150/3.5 last generation is about 100 Euro or a little less it seems?
A local photo store have two of these for sale at around 100 Euros. There you get some warranty.
Image attached of one of them. Very nice looking and I assume that is the latest version.
I think I have become too much fan of native Z-lenses with AF to get some "new" AI-s stuff.
I also have the 1st generation of the F-mount 70-200/2.8 VR. I guess this lens holds up well compared to the 75-150.
 

Finding a decent 3+ serial number here in Japan is surprisingly hard these days.

The used lens (and I suppose camera) market here is now dominated by idiots who barge into the reputable camera shops at the second they open, with huge roller bags. They swamp up anything new on the shelves and then peddle it on eBay as Mint++++++—, or shit like ‘read mint +++++’. They don’t care how inaccurate their descriptions are, and charge far too much. Sadly this is seen by the likes of Mercari and Yahoo auctions, where prices are raised accordingly.

Even worse, buyer’s rights are essentially nothing in Japan. No legal right to demand a refund.

If you are ever in Tokyo I recommend going to the likes of Fujiya or Kitamura or Map before doors open, and observe the scum with big bags. :-(

This is the case with photographic gear, but I am sure it is the same with manga, games, or anything else ‘Japanese’ the world is addicted to now.

Sorry for the rant, but this really gets my goat.

The Series-E 75-150/3.5 is my most used manual focus zoom. What's not to like? It covers a very useful medium telephoto range, which is perfect for portraiture, landscape, and closeups. It was also about the longest focal length I could easily hand-hold when shooting 100 ISO film, so I rarely used longer lenses. The close focus limit is very useful, and as Birna said, it handles closeup lenses (3T in my case) very well. The relatively fast constant f/3.5 aperture is also handy, much nicer than f/6.3 of many current zooms, only 1/2 stop slower than the big f/2.8 zooms, and allows nice narrow DOF if required. Background rendition is also relatively smooth and pleasant.

There are two versions of this lens. The first has a black plastic grab ring and early ones have the thin tabs at the rear of the lens which can easily get bent out of shape. I have the later version with the chrome grab ring and solid rear lens protectors. My version has not developed zoom creep.

There is nothing like this among the zooms currently available, the closest would be the Tarmon 70-180/2.8 which trades a slightly shorter zoom range for a more compact design. I sometimes wish for Cosina to bring out a modern version with improved coatings and glass, but they seem to be happy producing primes.

Today Cadiz was overcast, monotone with little contrast.

 Z6, 105mm 2.5 ai