Wow, thanks guys for so many quick answers!
I know I have to go with used lenses - I am ok with that.
At the begining i thought, that I would just buy A-version of 20/2.8 (like I did with A28/2.8) - but then I saw its price...
Sigma 24/2.8 is not significantly wider than 28/2.8, so I will rather skip it - but I watch one FA*24/2, cause price so far is interesting
Those 14mm lenses are huge (+their front element) - I chose pentax for its compact sizes.
I saw tokina 17/3.5 and its great comments, but it is not A version. I can buy it for 700PLN (~160 Euro) locally. I will try to negotiate price, cause for me those 160 Euros are too much for it.
Most of the lenses form
interested_observer's post that are bold are new for me, and probably hardly offered (even on ebay).
And how about those 2 zoom lenses I mentioned in my first post (16-45 and 17-50 tamron) ? Are they far away from primes? I thought also about F/FA pentax zooms - but 20-35 is very expensive and 24-50 is not that impressive range.
DA 21/3.2 is quite nice in terms of quality and size. But price should be lower...