LBA hits again. After discussing macro on the hardware-fr forum on Pentax lenses, someone posted a link to an eBay store offering what appears to be a very good macro lens: Vivitar 105mm/ƒ2.5 Series 1 Macro.
The Series 1 line of lenses seems among the best macro lens lines, made years ago (early 1990s says the vendor). Official price started at 249 US$, got it at 210 US$. Here is the eBay link. They were not really made by Vivitar by the way but manufactured for them by various companies like Tokina, Komine, Kino and others. See the [Wikipedia Vivitar]((https://en.wikipedia.org/wiki/Vivitar) page for details.
As you can see here and here, I've tried to take pictures of bugs and assorted animals (and flowers) but even though the Stak 135mm/ƒ3.5 is a very good lens, it is not made for macro photography.
This is really a very nice and very well built lens. A bit heavy, gets very long when trying to shoot 1:2 or 1:1 macro shots but I love it. All the pictures named macro-NN on Flickr were taken with it.
Serial number is 22403951, meaning it was manufactured by Kino Precision aka Kiron.