For the stated requirement (indoor of people in groups) it differs from the other lenses mentioned in that it's almost certainly going to need flash as it's soft wide-open as well as being slow. It might only be a stop or so slower than the 16-45 F4 wide open but by the time you get to a useable aperture it's more like 2-3 stops.

I quite often carry the Sigma 10-20, a fast 50mm prime and the Sigma 70-300 but the lens I use to fill in the gap is the Pentax 16-45 F4 and I think it'd be worth adding that to your list even if it is a stop slower than the others. I used to have a Tokina ATX-Pro 28-70 F2.6-2.8 and while it was a great lens I found the focal length range wasn't the most useful with an APS-C DSLR so eventually sold it. Having a gap between 45mm and 70mm (or 45 and 80mm if I'm carrying an 80-200 F2.8 instead of the 70-300) I've never found to be an issue.

If I need more speed for interior shots I tend to use cheap manual focus primes (e.g. Sigma 24mm F2.8, Vivitar 28mm F2).

I've seen similar problems being caused by defective RAM.

Very nice.

I used to work in a tower block just behind the BOC building and could see it from my office window.

Pentax K10D, Tokina ATX-Pro 80-200 F2.8

They pop up reasonably frequently on Ebay - they can also be badged as Vivitar, Pheonix, Voigtländer or Pentax so it's worth looking for those as well. There are none listed in Pentax fit at the moment though (other than a Pentax badged one in an Ebay shop for a ludicrous $379.99) but it's worth keeping watching as when they do come up they can be very cheap (mine was £37 in boxed/virtually un-used condition).

You can get the Cosina 100mm F3.5 Macro (or the re-badged Pentax version) for less than the price of a 50-200.

I bought my FA* 85mm F1.4 when I'd got into portraiture, including using studio lights. I also found it useful for theatre & dance type photography. It is very specialist though so despite being probably my most valuable lens it's not one of my most used.

Were you tempted?

I'd expect an FA* to sell for a bit more, but perhaps not a lot more.

I won an Ebay sale of a FA 135mm F2.8 a couple of years back for under £100, however the lens mysteriously went missing in the post and my payment was quickly refunded. My suspicion was that the seller (a photography shop) didn't want to let it go for that little.

I'm not sure what an FA* 85mm F1.4 would go for however I was watching an A* 85mm F1.4 recently and it was at £430 with some time left to go (I don't know what it finally sold for though).