I do not believe Pentax ever had a bad macro lens. I have 2 different 100mm ones and a Pentax A 50mm f/2.8. The DA 100mm f/2.8 WR is simply a masterwork.
There is also the DA 35mm f/2.8 macro Limited, I do not have it but it is highly regarded,
Your choice should be based on the focal length you need and the features you need. If you need autofocus or not, if you need auto aperture or not. Some of the older manual lenses are quite good and less expensive but you need to be comfortable using them in all manual mode.
There is also an A*200mm f/4 macro but that goes for well over $1,000 if you can find one.
Here is the link to the FA 50mm f/2.8
https://www.pentaxforums.com/lensreviews/SMC-Pentax-FA-50mm-F2.8-Macro-Lens.html