[redcat]

I recently got my first Pentax, a K-1, and I do like it, but there still aren't very many lenses for it, and it seems that people suggest these extremely expensive limited lenses as the saviour of the system.

Welcome to the Pentax system, I did try many lens before and now that I own the FA 31 and FA 77 my LBA is cured (I don't try the FA43 because it's too close to the FA31 and FA77), you can see many review on these two Limited in the review section of the forum, here are mine :
SMC Pentax-FA 31mm F1.8 AL Limited Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-FA 77mm F1.8 Limited Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database
I have nothing to complain about the image quality, build quality or color rendering of these 2 lens, images worth a thousand specs The AF maybe a little noisy because they use screw drive but it's not the most important factor for me. They can be bought for a reasonable price at Market Place (ex : https://www.pentaxforums.com/forums/24-photographic-equipment-sale/332438-sal...7mm-black.html)
If you can only get one lens, get the FA77mm, very small and sweet bokeh and sharp and SHARP

[pakinjapan]

Am I wrong, am I missing something about the system? Is it their nostalgic charm? Do they capture that quintessentially Pentax light that each epitomises what it is to shoot Pentax (just like the creamy Leica-look. Or that Hasselblad feel)?

I used to ask similar questions long ago, but since I move to Japan, and every big electronic stores (that sale Pentax) have almost every Pentax lenses for people to test which I take full advance of that fact. Well, I am not going to say they can make a better image or they have better color or even sharper.
But in short, yes, they are difference. The build quality is always better with Limited lens. "If" I can find 2 lenses with similar focal length and they offer similar image quality, one a more expensive limited, and one not, I would go for Limited anyway. It is the same reason why sometime I walk longer distance to get a more expensive cup of coffee when I know a cheaper cup of coffee at 7/11 around the corner can give me caffeine too.

Beside that, I don't think the DA limited are expensive. for FA line up, well, I think the 31 is a kind of expensive but not too expensive still.
For every limited lenses, build quality alone can justify its prince.

I see you mention about FA43;
I try both 43 and 40 limited with K-1 quite often because I was thinking of getting this combination. My 2cents, I like DA40 on K-1 more. it focus faster, pancake, cheaper, lighter and it is very sharp on K-1.