If the stitching were fixed I would say it was worth at least $400.
The cost to repair the stitching depends a lot on where it is at and if you have a person nearby to fix those types of things. Some stitching is easy to sew and some is difficult depending on where it is at.
I have had a heck of a time in the past finding anyone to repair saddle stitching. The boot repair people didn't have a clue and the custom saddle makers were too expensive. Eventually I learned how to sew from a friend and can do many of my own repairs now myself.
If you have a saddle shop in town you can get a quote on the repair. But either way $175 sounds really cheap for a comfortable, basically sound saddle.