Looks like there's a copy available on the marketplace
here. Seller is asking $390 and there has been at least one inquiry about it. Doing a quick search of eBay, it seems that the price on the Pentax website is actually somewhat decent.
I have one of these lenses and it has become my favorite. Granted, I only have this one and the FA 50/1.4, so my collection is not exactly large. I got my copy on the marketplace for $415, I believe. They seem to pop up about once or twice a month. I have not regretted this purchase one bit. My copy puts out acceptably sharp images wide open, and as is the custom, becomes much sharper when stopped down a bit.
I would say don't get any closer to 50mm than 35mm. I quickly ruled out the DA 40mm because it's too close to 50 for my tastes.
I went with the FA 35/2 mainly because of the factors of price and max aperture. I wanted a wide lens but couldn't afford an FA 31 limited. If I had a lot more money, I would've gotten the FA 31 because it's slightly wider and slightly faster. I also strongly considered the DA 21/3.2, but the 3.2 aperture seemed a bit slow for my shooting, which is mainly indoors.
Also be on the lookout for the Samsung Xenogon 35mm f/2. It's the same lens, just sold under the Samsung brand. And probably for cheaper, too.
Feel free to ask me more about the lens.