I've been a Pentax fan for 30+ years and always found them good cameras. The Programme A was introduced in 1984 and has quite a lot of electronics, so this might be a factor to consider (replacement mechanical parts can often be sourced easier than electronic circuits).
If it were a all-mechanical Pentax (MX or earlier?) or even the rather under-rated LX, I'd have no hesitation in having a repair at a reasonable price. I'm not sure from your post what your figure is for the proposed repair? If it is £163.50 it sound a bit steep unless it includes a full CLA, and you attach any sentimental value. If you just want a good working Pentax it might be looking at all options, as Hatchetman suggests.
Just my thoughts.